Forget y'all...try translating "all y'all". That one is enough to make a pretzel out of any language!
Seriously, though, I lived a year in south Texas, and we gained an appreciation for many quaint "southernisms". Of course, that word would have an entirely different connotation in Ireland.....
I have seen some instances of parts of words left off, both in poetry and in daily usage in Irish. Usually, it seems to be done when the result should be obvious to the reader or hearer. I'm having trouble coming up with a good example, but often "agus" (and) seems to be abbreviated 's, but sometimes that also seems to be an abbreviated form of the copula. I don't know if you can always tell which is which, or if it's always the copula serving as a combination verb and conjunction.
The first two lines of "Maidín i mBéarra" are:
Is é mo chaoi gan mise maidin aerach Amuigh i mBéarra im’ sheasamh ar an trá,
I assume the abbreviated "im'" is possibly for "imirt" but not sure how the context works or is used here. Someone may be kind enough to explain. My online dictionary doesn't give a precise definition of "imirt", but it seems to mean "play"?
Dale D