Just to add a small note to Ade’s response – the important part there is that atá is on its own pronounced atá /əˈtɑː/, that is, the stress is on the second syllable and the first a- is the reduced unstressed /ə/. It’s not /ɑtɑː/. (In Old Irish the verb was at·tá where at· was an unstressed preverb added to the stressed root ·tá; in Early Modern Irish the initial a(t)- was dropped everywhere outside of relative clause context (and sometimes here too), and the a- was reinterpreted as a “relative particle” – but anyway, whenever it’s still there, it’s unstressed)

Well, in Southern England, we have the "intrusive R". "The sofa at work" is pronounced "the sofar at work". I believe they do things differently in the US, ...

I was wondering if the stress was on the second syllable of atá.

Thank you!

Most words in Cois Fhairrge Irish have the accent on the first syllable, so atá is an exception. Abhaile (home, in a homewards direction) is another exception. So you should bear in mind that in nearly every case words have initial stress. This helps a lot. In Munster Irish, it is a different situation entirely. You can listen to the pronunciations at https://www.teanglann.ie/ga/fuaim/abhaile, and for Cois Fhairrge you should choose the middle dialect (Cúige Chonnacht).

In the book Learning Irish (by Ó Siadhail) there is the phrase, "Gabh mo leithscéal!" with the English equivalent as "Excuse me!"

Since usage in Hiberno-English, UK English, and American English sometimes differ, in which of the following contexts might one use this phrase?

1. If you need to interrupt someone (you probably don't know well) to ask them a question or speak with them.

2. If you accidentally step in front of someone or bump into them.

3. If you burp or fart.

4. Other contexts?

All of those (although as an Englishman I know nothing about #3; we don't do that). See https://www.focloir.ie/ga/dictionary/ei/excuse+me