Where did his middle initial "Z." come from?  I have yet to find a primary source using a middle initial.
If Nicholas was born in 1710, he is too young to be having children in 1725.  To be the parent of the eldest child (Sophia, b. 1725), he would have had to have been born no later than ca. 1706.

.  Sophia CORBIN, b. 1725; m. Thomas MARSH 

.  Benjamin CORBIN, b. 1730; m. Sarah SIAS 
.  William CORBIN, b. 1744; m. Betsy BROWN 

.  Elizabeth CORBIN, b. 27 Nov 1734; m. Edmund DEDMAN 

.  Abraham CORBIN; m. Rachel MARSHALL 
.  Joseph CORBIN
.  Shadrach CORBIN, b. 1732
.  Nathan CORBIN, b. 1738; m. Sarah JAMES 

1.  Robert W. Barnes.  1989.  Baltimore County Families, 1659-1759.  Genealogical Publ. Co., Baltimore, MD (Broderbund CD-195).  Boldface added.

p. 30

BARRETT, JOHN, d. by 24 March 1717/8 having m. Alice, extx. of Nicholas Corbin; his will, 21 June 1717 - 24 March 1717/8 named "grandson" Nicholas Corbin, eld. s. of Edward Corbin, also John Royston, James Wells, and John Keith, s. of Alex., wife Alice to be extx.; she was alive in Nov. 1718 when Zacheus Richards, age 2, was bound to serve her...

2a.  John Davis.  1996.  Baltimore County, Maryland, Deed Records, Volume Two: 1727-1757.  Heritage Books, Bowie, MD.

p. 40	3 Sep 1733, Nicholas & Elinor Corbin, planter, of Baltimore Co., Maryland, to Philip Lindall, planter, of same, 195 acres...John Barrett devised 1 Jun 1717 to said Nicholas. Signed Nicholas (x) Corbin. Wit: Thomas Sheredine and Thomas (x) Harris.
p. 362	11 Jun 1753, Nicholas Corbin, of Baltimore Co., Maryland, to Thomas Marsh, of same, chattel goods. Signed Nicholas (x) Corbin. Wit: Thomas Franklin and Ruth Franklin.

So this is where the 3 Sep 1733 "marriage date" came from.  They weren't married on 3 Sep 1733, they were married before 3 Sep 1733 — a distinction worth making.  Another source states John Barrett signed his will 21 Jun 1717, not 1 Jun, but either way, transfer of title to the land could not have taken place until after the death of John Barrett, in 1718.  The sale in 1753 without Eleanor indicates she has passed away (or that they had divorced, which is highly unlikely).

2b.  John Davis.  1996.  Baltimore County, Maryland, Deed Records, Volume Three: 1755-1767.  Heritage Books, Bowie, MD.

p. 29	29 Mar 1755, Nicholas Corbin, planter, of Baltimore Co., Maryland, to John Ensor Jr., of same, £5.5, head of Back River. Signed Nicholas (x) Corbin. Wit: Nicholas Ruxton Gay and William Lyon.
p. 320	1 Sep 1766, Nicholas Corbin, farmer, of Baltimore Co., Maryland, to William Winchester, of Frederick Co., Maryland, £10, 18 acres... draft of Patapsco Falls. Signed Nicholas (x) Corbin. Wit: James Ager and Thomas Franklin.

Nicholas appears to have remained unmarried after being widowed.

3.  Richard B. Miller.  1985.  "Index to the Signers of the 1768 Joppa Petitions of Baltimore County, Maryland."  Maryland Genealogical Society Bulletin 26(4): 393-428 (Broderbund CD-208).

p. 393

By 1768 it had become apparent that the once thriving port of Joppa on the Gunpowder River was no longer capable of handling the commercial shipping for which the port facilities of the rapidly growing port of Baltimore Town on the Patapsco River were needed.  Largely as a result of this shift, it was obvious to most people that Baltimore was a far more appropriate seat for the county government.  The Assembly, however, with great fairness, chose to make this determination on the basis of a popular referendum and ordered that petitions, both pro and con the change, be circulated throughout the county to be signed by all adult males over 18 -- virtually a census of adult county residents in 1768...

p. 400

Corbin, Nicholas, 532

Page numbers after individual's names are those of Appendix VII, Vol. LXI, Archives of Maryland, from which Miller compiled this alphabetical index.  Those opposing the petition have the page number underlined. 

4.  Letter, dated 19 Jun 1858, from Keziah (GREENLAND) SHANAFELT of Clarion Co., PA, to her son, Thomas. Keziah is a granddaughter of Benjamin & Sarah (SIAS) CORBIN.  The letter is in the possession of  Laurel Shanafelt Powell of Colorado; Lorinda Clendenon Greenland generously posted a transcription at her web site. 

My mother's father was Benjamin Corbin; her mother Sarah Sias.  I think they both came from England.  Their ancestors lived in England where some of them still remain.  My two grandfathers (Moses Greenland and Benjamin Corbin), as I understand, lived about four miles apart.  The children of both families attended the same school just thirty miles this side of Baltimore near Winchester.  I never saw Grandfather Corbin.  He died when I was young.  I often saw his youngest brother William.  He came to Huntingdon.  While young he married Betsy Brown, sister to Mrs. Weaver's father.  He lived near Raystown Branch but died in Huntingdon.  Many of his descendants live there yet.  He had a sister, lived in Ohio.  Her family was said to be very wealthy.  I think her name was Marsh. He had other brothers, too, but I am unacquainted with their history...

5.  LDS.  Family Search: Internet Genealogy Service: International Genealogical Index (IGI).

Shadrack CORBIN Birth: Abt. 1732, <>, Baltimore, Maryland Father: Nicholas CORBIN; Mother: Eleanor Source: [patron submission]

6.  Broderbund.  World Family Trees.  Vol. 40, Pedigree No. 356.