Tradition was to marry in the bride’s church, though that doesn’t appear to have happened in this case as Elizabeth was living in Tartaraghan and they married in Drumcree Church of Ireland.
I would check both Drumcree and Tartaraghan’s baptism records for Elizabeth and perhaps her siblings.
Drumcree’s baptism records start in 1788, Tartaraghan’s in 1825. However they don’t appear to be on-line anywhere. There’s copies in PRONI (the public record office) in Belfast but if you can’t get there in person you would need to employ a researcher.
Researchers in the PRONI area: http://sgni.net
I see from the marriage certificate that both the fathers were labourers. They tend to be very difficult to trace, as they often moved about to follow available work. I checked Griffiths Valuation 1864 but there’s no Watson family in Canoneill. There is 1 Craig household in Breagh (Tartaraghan). That was Joshua who had plot 3D(b) which was a labourer’s house on Thomas Trueman’s farm. Possibly a relation of Elizabeth Craig? The Valuation Revision records show Joshua remaining there till 1891. He’s not in the 1901 census, but I can’t find a death certificate for him either so not sure what became of him.
For Michael Watson’s death it’d be a question of searching the relevant records in the area in the same was as for Elizabeth. Starting perhaps with Drumcree Church of Ireland. Do you know what denomination he was?