Depends, these things change from offical to offical and over time.
I take it she is not in Ireland at the moment, was she ever? Geting married here is the simplest for paper work. (problem is getting here!) Irish paperwork, so once married drop into the GNIB and have her status changed to resident (Stamp 4). They give a 1 year visa first time and they will extend it to the expiry date of the passport the next time it is renewed, i.e. if both of you turn up a year later. I have never heard of anyone being kicked out if married here, as there is no arguing over Irish paperwork.
Getting married abroad is another story, paperwork needs to be translated, verified, re issued by central government rather than region you were married in, proof of living as man and wife etc etc.
You should give your local registry office a ring for the rules etc You could also try the GNIB, but not too sure they bother to answer the phone!