The townland on the 1849 marriage cert that John gave looks to be Candy in the parish of Magheraculmoney. Unfortunately I can’t find a townland of that name in the parish. There is a Cady or it’s possibly an obsolete name. Eliza’s was Knockaraven in the parish of Dromore, Co Tyrone. Tradition was to marry in the bride’s parish. The church was a Presbyterian church so you would expect her to have been brought up a Presbyterian. (So Scottish origins, as you would expect with surname like Gilmour).
Dromore Presbyterian church only has baptism and marriage records from 1835 onwards so you may not be able to trace her baptism. However there are several Gilmour farms in the townland in Griffiths so you can probably trace her descendants forward if you wish.
There was a Christopher Crozier in Cady, in Griffiths so that may be John’s townland or origin. However, the townland that Sarah Crozier was born in is Gorteen. So we know John’s family had moved there. Griffiths for 1862 shows John Crozier there on plot 4 which was a farm of 20 acres & 3 roods. The revaluation records show him acquiring plots 7 & 8 – another 12 acres in 1876, then being replaced by James Beacom in 1887. However it then goes back to John Crozier and then to William Crozier in 1897. So John may have died around that time. (Possible death you might want to look at was John Crozier 23.9.1893 aged 80, registered in Irvinestown).
https://www.nidirect.gov.uk/proni
The 1901 & 1911 censuses show William and family:
http://www.census.nationalarchives.ie/pages/1901/Fermanagh/Kesh/Gorteen/1354427/
http://www.census.nationalarchives.ie/pages/1911/Fermanagh/Kesh/Gorteen/520471/
Probate abstract:
Crozier William of Gorteen Kesh county Fermanagh farmer died 16 July 1943 Probate Belfast 14 December to Albert Anderson justice of the peace and William Crozier farmer. Effects £282 1s.
The full file should be held in PRONI.
That farm today is a couple of miles south of Kesh village, near Castle Archdale.
You'll likely need to get a researcher to look up the 1860 and 1861 baptisms. Try Dromore Presbyterian church records at PRONI. (Or you could pay PRONI to do it, but they are quite expensive).