An Hobad translated by Nicholas Williams (I know it’s not the best example of Irish out there – but I believe it shows well modern publishing standards, and I happen to own the book) uses double quotes, eg.:
Quote:
Seo mar a léigh sé:
“Tóirín agus a Chomplacht chuig an mBaigíneach Buirgléir, beannacht! Táimid fíorbhuíoch díot as an bhfáilte fhlaithiúil a chuir tú romhainn agus glacaimid go fonnmhar leis an gcúnamh proifisiúnta atá tú a thairiscint dúinn. (…)
“Táthar ag súil go mbeidh tú ann go tráthúil.
“Is sinn le meas mór
“agus le fíorómós,
“Tóirín agus a Chomplacht.”
“Ní fhágann sé sin ach deich nóiméad againn. Beidh ort deifriú,” arsa Gandalf.
So it looks like the usage is identical to British English usage.
Not sure about Oxford comma, I’ve found such examples:
Quote:
“(…) Lig dom Bíofúr, Bófúr, Bombúr, agus go háirithe Tóirín a chur in aithne duit!”
but:
Quote:
Bhain Dóirí, Nóirí agus Óirí amach fliúiteanna as áit éigin laistigh dá gcótaí.
An Ghaeilge, Polish textbook for modern Munster Irish (Kerry, I believe) by Aidan Doyle and Edmund Gussmann, also uses double quotations in Irish texts (“this kind,” also with comma inside the quotation marks), but I am not sure if there are any examples of series where Oxford comma would be applicable. And this textbook was typeset, I believe, by Polish people without much experience in Irish typesetting – so probably it was based on English typesetting anyway.