Why is there a g before the c in my above question?
An urú, yes. Your other example is a seimhiú. Both essentially make speaking 'easier' and more natural but it does complicate grammar.
My colleague learned Irish in about 2 years I think. She had kids under 5 at the time and wouldn't have had any knowledge of Irish prior to beginning teaching here. It is possible - didn't say it was easy - but it is achievable.
You would have to get to a decent standard of Irish OP as you will have interview questions in Irish.
Also worth noting, but I'm not 100% sure, but to teach in a lot of Irish primary schools, which are at least 80% Catholic, you would be required to teach the Catholic curriculum.
Yes this is true (but how much religion you'll have to teach varies...most schools I've been in just pay lip service to it). You would have to get the RS teaching cert to certify you for it. I know Maynooth do a course for it but not sure if other places do too.
The school won't be paying your wage themselves so they don't care how high up the payscale you are. I agree with the others, experience is valuable.
Secondary teaching is a possibility but some subjects have a glut of qualified teachers. It can be hard to get a job in certain subjects and you may get very low hours - so that's another area to research.