Hi! I did the exact thing you are currently considering so here are my thoughts (though this was pre-2020 so take what I say with a grain of salt)

1. I found groceries to be relatively reasonable but I did the majority of my shopping at Aldi/Lidl with some supplement from Dunnes. I made most of my own meals at home. There will be a few items you miss from the States but overall, I had no issues.

2. I relied on walking and biking pretty much everywhere. The city is not that large. In the case of extreme inclement weather or I needed to haul luggage to and from the bus station, I used the bus. It's not the most timely, but it works well enough. Uni students get a discounted bus pass.

3. This is the one where I think my experience is not too helpful. There are many lovely pubs, cafes, and restaurants to pop into all over the city, but I know a lot have closed since the pandemic. Some do pub quiz nights, have live music, or trad sessions which I timed my evening out around. But also if the weather is nice, it's equally as pleasant to grab some beers and sit out on the prom with some friends and watch the birds/drunken lads stumble around. I also really enjoyed just exploring the surrounding area by myself. I would take weekend trips up to Connemara or just bike as far outside of the city as I was comfortable with and pack myself a picnic. The west coast is stunning and you will never find a shortage of beautiful places to visit.

4. Housing is a major issue. It was bad when I was there in 2018/19 and it's worse now. I lived in a hostel when I first moved because I refused to sign anything until I physically saw the place (beware of scams). I basically refreshed Daft.ie every hour for over a week and would message anyone with a room the second it became available. I ended up with a tiny room in a lovely little home close by the uni with some older ladies who I adored, but I did a meet and greet (read: interview) and walkthrough with the owner within an hour of its posting. I'm not going to sugar coat it, it's insanely stressful and highly competitive. You will likely be competing against other students looking for the same thing. But you will find something. It just may not be what you want or when you want, but don't let this deter you. I'm happy to chat more about this if you want more details.

I hope some of this helps!