I can help you out on some of your questions and mysteries:
"Some records indicate that Thomas Jefferson DeVore was born in 1861 and died in 1899."
Yes. You can see details about his censuses with his mother, his estate inventory, a document submitted by Alzada when she applied for benefits from John Berry's Pension that backs up the date of the inventory, and his age at the birth of his first son John Gordon Devore. See text here http://worldconnect.rootsweb.ancestry.com/cgi-bin/igm.cgi?op...
and if you have Ancestry you can REALLY see them at http://trees.ancestry.com/tree/35326675/person/18783142895
" Minor: Sarah E Marrow, et AL [who is she??]"
She's Sarah Elizabeth Berry who married Christopher C Morrow. The et al are her sister and brother, except William's name got crossed off at the last minute--maybe when they read the instructions?
You can see the actual application at http://trees.ancestry.com/tree/35326675/person/18783143044
"cem. record - J. C. DeVore " [census record has him listed as J. G.]"
So does the headstone if you look carefully but the person who "read' the cemetery didn't spend much time being accurate. He didn't know that not all capital G's have a cross bar in old writing on headstones, but they do have a different shape than a capital C. The G's have a broad base before the vertical line to make the G. You can see it in this stone but it takes a while to get there. http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=de...
It's believed by most people who read censuses and historical documents that the other Devore dates are not accurate. We know who made up the 1845 date and why, but we but haven't figured out yet why she didn't catch Alzada's listing a widow in the 1900 and 1910 censuses and where she pulled Thomas Jefferson Devore's mythical death date of 1925 from. http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=19...
. There is no one on the 1850, 1860, 1870, 1880, 1900, 1910, or 1920 censuses who matches this description.
Find-a-Grave is too subjective sometimes to be used a reference other than hints. . http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=de...
; For example the person who has Alzada's death date listed as 1910 once told me that she was still alive at the 1917 birth of her grandson Pierce.