The obvious reason would be to get the group discount on pricing (see below), but the most important reason is to gain the support of the project administrator and to facilitate the sharing of your results and lineage.  Very often the project admin is an expert in the surname, so can best help you understand what your results mean in terms of your paper genealogy.

A direct male or direct female line is one where the gender of the ancestors doesn't change from generation to generation.  Each of us has only two such ancestral lines, one all male (patrilineal) and one all female (matrilineal).  If your line to your ancestor zig-zags between males and females, you will not be able to participate in a project based on that ancestor.

Everyone inherits their mother's mitochonrial DNA, so both males and females can be mtDNA tested.  But because only males have inherited a Y-chromosome from their father, only males can participate in Y-DNA surname projects.  
 

Male	Female	Male	Female	Male	Female	Male	Female
Male		Female		Male		Female
Male				Female
Male test subject has a Y-chromosome and mitochondria

Male	Female	Male	Female	Male	Female	Male	Female
Male		Female		Male		Female
Male				Female
Female test subject has only mitochondria, no Y-chromosome

With regard to Y-DNA testing, all levels of testing are useful for something, but most researchers have found the more markers tested the better.  It partly depends on whether you turn out to have a common haplotype or a rare one, but of course, you don't know that until after you've been tested on at least 12 markers.  It's parallel to the situation with names, that is, identifying you is more difficult if you are John SMITH than if you are Engelbert HUMPERDINCK.  In identifying John SMITH, it helps greatly to know his middle initial and, better yet, to know his middle name.  Adding more markers to someone's haplotype is parallel to knowing John's middle name to help separate him from other John SMITHs.  I guess we could think of markers 1-12 as the surname, 13-25 as the first name, and 26-37 as the middle name — and 38-67 as the birth date and place!  In other words, the more clues you have to the identity, the more confident you can be of the identification.  And the more common the name or haplotype, the more clues you need.

With regard to mtDNA testing, the mtDNAPlus test is definitely preferable, to narrow down the size of the group with whom you match, and the FGS test would be the most definitive.

No.  Your sample will be kept in cold storage for a guaranteed 25 years, so it will be available for additional testing.  It can be assumed that, over the next few years, more refined tests will be discovered.  Having your sample in storage will make it possible to have these tests done without submitting additional samples.

If you get an unexpected result, yes.  But even if you get an expected result, one reason to test addtional family members is to get them interested in their genealogy and identifying themselves with their ancestry.  DNA testing makes a wonderful gift to bring your family together.

But just as we are warned not to do our genealogy unless we can handle finding out something we'd rather not have known, anyone being DNA tested has to be prepared for an unexpected result because about 2-5% of people tested turn out — through hidden adoption or paternity — not to be descended from their "paper" ancestor.  Such a result is known as an "NPE" (non-paternal event).  In the case of an NPE, the testing of cousins (beginning with a first cousin, then progressing to increasingly distant cousins) can pinpoint where the NPE took place.

While people today are generally open about adoptions, in the past an adopted infant was much less likely to have ever been told they were adopted.  Likewise, a wife's infidelity was more likely to be hushed up than to result in divorce, even if the infidelity was uncovered.  For these reasons, assume that an NPE occurred in distant generations, rather than near ones, and don't jump to any conclusions because you get one.  Still, consider the feelings of everyone in the family before bringing the NPE out into the open.  By the way, this is the real reason to keep this testing anonymous, not because these STR test results reveal anything medically important about you (they don't).  So, I recommend quietly testing yourself, first. Then, after you have the result, decide whether to share the news with your family (or your fellow genealogists).

There is also some logic to the idea that everyone doing their genealogy would do well, at the outset, to test themselves and at least a first cousin, just to be certain they don't spend literally years working on the wrong surname. On the other hand, if other descendants of your progenitor have already been tested and you match them, you have your answer and need without testing any near cousins. 

There may be some urgency involved with testing your family's senior members.  For example, my father was 86 years old when I paid for his testing.  He even joked with me at the time, "Oh, you want to get this done before I die."  Well, yes, actually, and I'm relieved that his testing was completed because he has since passed away.

Yes.  Typically, one would first join their surname project, then, once results are returned, possibly join one or more appropriate haplogroup, regional, or ethnic projects.  There's a blue Join button on your member page that will allow you to request membership in additional projects (pending approval of that project's admin). There is no cost for joining additional projects.

Yes and No.  For males, your Y-chromosome came from your father, and only from your father, so Y-chromosome DNA testing will be of no help in elucidating your mother's ancestry.  To research your mother's surname (i.e., her father's patrilineal line), you will need to get her father or one of her brothers or uncles or nephews of that surname to be tested for you.  For both males and females, it is your mtDNA test that will reveal your ancestry on your mother's matrilineal line.

Taking the sample is simple and painless, just read the directions carefully and don't hurry.  The kit arrives by mail and contains three plastic sticks — rather like small toothbrushes, without the bristles.  You take the sample by rubbing the inside of your cheek with the stick, then dropping the detachable tip into a vial.  You take the samples at least eight hours apart.  Then put the vials in the provided mailer and return the kit by mail.

You establish your level of privacy by the way you join and the options you select.

If you want complete privacy, you should not join a project, but simply order and pay for your testing on your own.  That way, your identity and results are known only to you (and to FamilyTreeDNA, obviously).

If you join a project, the project administrator knows who you are (i.e., has access to your full name and contact information), but only your test data, lineage, and surname — not your given name(s) — will be placed in public view on the project's web sites.  The administrator will not reveal your identity to anyone, not even to other project members or administrators.  That doesn't prevent you from revealing yourself, it just means that neither FTDNA nor I will do it.

By signing the Release that comes with your kit, your name and email address will be shared with others tested at FamilyTreeDNA whose results match yours (and vice versa), but your name and email address will still not be displayed at the project web sites nor be released by the project administrator.  Signing the Release is a condition of joining this project as it is unfair to refuse to share your results with others when others are sharing their results with you.  If you don't want to be the contact person (i.e., if you don't want to be emailed by "matchees"), we can substitute my name and email address as the contact person.

You do have the option of Restricting match sharing to just the members of your project, rather than with everyone else tested at FamilyTreeDNA, the latter obviously being a much larger database.  Please note that the FTDNA database is not searchable or browsable, not even by project administrators, much less by the general public, which has no access to the FTDNA database.

If you want to get the most from your testing, then share the most, that is:  join a project, sign the Release, remove the sharing Restriction (via the checkbox at your member page), and upload your results to Ysearch (see next FAQ).

Lastly, and speaking personally (not as a representative of FamilyTreeDNA), I frankly do not see the need for privacy.  My mtDNA FGS (Full Genetic Sequence), including my identity, is online at GenBank (EU979542).  You should be much more concerned about someone knowing your Social Security number or reading your bank account number off your checks or your credit card numbers off your sales slips.  (And I'd much rather have someone know my haplotype than my weight!)  I do have this one caveat:  I recommend keeping the fact that you are being tested quiet until you've seen the results because, if your results uncover a hidden adoption or illicit paternity, you may want to limit with whom you share that information. I made certain my first cousin and I were an mtDNA match before I "went public" with my HVR1+HVR2 results, and I had a medical analysis done before I went public with my FGS results.

See also FamilyTreeDNA's privacy policy.

Ysearch.org is a publicly available and searchable database on the internet, sponsored by FTDNA, but open to anyone regardless of where they were tested. Once your test results have returned, the upload is a few easy clicks from a link on the "Y-DNA Matches" tab of your member page.

Even if you upload your data to Ysearch, your anonymity is still maintained if you so wish.  At Ysearch, only the test results and surname of the test subject are necessarily displayed. You have the options of including the name and origin of the most distant ancestor, uploading a GEDCOM, and/or revealing your name as the contact person (if you wish to remain anonymous, just enter "name witheld" in the contact name field). Visitors contact you via a form that reveals neither your name or email address, giving you the option whether or not to respond and reveal yourself.

The question then becomes, why upload to Ysearch? One reason is to seek a match in a larger database, one that includes individuals tested at other companies, not just FTDNA.  The other is to make your data available to researchers, in particular, to ones studying larger issues, at the paleoanthropological level.  Anything you do to help them ultimately helps you better understand your origins.

Lastly, I hope you will upload just to have mercy on your project admin.  If you don't upload your results, I have to manually enter your test data into Ysearch every time I want to check to see if you have any matches.  Please spare me this tedium!

Results from STR (Short Tandem Repeat) testing should correlate with results from SNP (Single Nucleotide Polymorphism) testing.  In other words, haplotypes should correlate with haplogroups, and they do.  Therefore, in most cases your haplogroup can be deduced from your haplotype.  In cases where the prediction of the haplogroup from the haplotype is weak or equivocal (most likely due to a rare or unique haplotype), FTDNA will do a "backbone" SNP test (without charge) as part of its "haplogroup assurance policy."  This policy means being STR tested at FTDNA assures that you will know your basic haplogroup with certainty, without the added expense of a backbone SNP test.

Deep SNP testing determines your haplogroup subclade and is offered by FTDNA without having to submit another sample.  This determination (and, thus, this testing) is not a requirement for participation in the project, but I hope you will consider doing it, for a number of reasons.

One reason is simply to "contribute to science."  Every one of us who undergoes both STR and SNP testing is contrbuting to the databases that allow these correlations to be made and is contributing to the success of researchers engaged in reconstructing human origins.  And then, there's your own curiosity.  I'm fascinated by the progress being made, and I find it far more meaningful to know that I'm part of the process of discovery and advancement.  If you want recent history to come alive for you and your children, do your family's genealogy.  If you want human history and earth history to come alive for them, have the family DNA tested — and once you have your test results, join the National Geographic Society's Genographic Project (a few easy clicks on your FTDNA member page).

On the practical side, haplogroups are a logical way to organize the project because people in different haplogroups have a zero probability of being closely related, so breaking up the project by haplogroups is simply useful. 

FamilyTreeDNA is a for-profit business.  The surname and regional projects based at FamilyTreeDNA are administered by volunteers (I'm a retired zoologist/paleontologist whose hobby is genealogy).  This arrangement is parallel to the mailing lists at RootsWeb.com and the message boards at Ancestry.com, which are administered by volunteers, but owned by a for-profit business.

No.  The sample belongs to you.  Your sample will be kept in storage at FamilyTreeDNA for 25 years, in case you wish to have more tests run (without having to submit another sample) — or you can have the sample destroyed if you so direct.  Your test results will be made public on the project's web site free of charge, which means there can be no incentive for anyone to try to sell the data.

FamilyTreeDNA offers a variety of tests and services.  Please see descriptions of products at their web site:

The prices given there are the "list" the prices you will pay if you do not join a project.  Those who join a project will enjoy discounts on these tests (see table below).  The "bundled" tests represent a savings over purchasing tests separately. 

If you have already been Y-DNA tested at another laboratory and want to be totally comparable to other members in the project, you can opt for a Conversion Kit.  For males, this kit will bring you up to 37 markers and make you eligible to upgrade to 67 markers at the group rate (see below).  For males and females, the conversion gives you the benefit of being in the FTDNA database with comparable markers, where you will automatically be notified of matches in their otherwise private database.

It's ultimately cheaper to purchase the maximum markers from the outset.  Upgrading the number of markers in stages is easier on the pocketbook over the short term, but will cost more in the long run:

If you purchase 12 markers, then upgrade to 25, then upgrade to 37, then upgrade to 67, your total cost would be $296, compared to purchasing 67 markers at the outset for $248, for an added expense of $48.  With regard to mtDNA testing, adding HVR2 later brings the total cost to $204, whereas if you get both HVR1 and HVR2 tested together, from the outset, the cost is $189, a savings of $15.  On the other hand, you may be in a situation where the additional long-term cost may be worth it to spread the expenditure out over time.