You USA license is fine and take every bit of insurance offered when you rent the car. Many roads in Eire are tiny. There are hedges and rock walls.
Easy to scrape car doors, ruin side view mirrors.
Just get the coverage. You’ll be driving on the opposite side of the road so there’s a bit of a learning curve.
I’ve driven the island 3 times and happy to say no scrapes, collisions or near misses.
However as a passenger with a friend she took off both side view mirrors in a vain attempt to negotiate driving through a village where there was a soccer match. People had parked along the the wee roadside. She wouldn’t turn back, had to go through. Stubborn. I drove from that incident on.