Questions about connecting flight to Rome via Dublin

You do not have to get your luggage, you will go through customs in Rome, which will just be a matter of walking out the green door.

I changed there once on the way to Duesseldorf and had no problems. It was less than 90 minutes. I can't even remember if there as a passport check. Ireland is not part of the Schengen Treaty, so you will go through Schengen immigration in Rome.

We fly from Boston to Italy and have not chosen an Irish transfer simply because it make any sleep even less likely - ditto London. Our preferred transfers are Munich or Zurich.

My daughter took the Bos-Dub-Rome flight last May with no problem, and we've booked the same for mid March. But we will not be checking luggage on the way over, (she didn't check a bag either) mostly because when we land in Rome we're heading out by train so if the luggage is lost or delayed, it would be more difficult to catch up to us than if we were going to be in Rome for a few days. We will be checking luggage on the way home, just to lighten our load and then we won't be worried if our dirty laundry doesn't arrive at the same time we do.
The previous point about disturbing sleep is well taken, but we got such a deal on our flights.... hopefully we won't regret it!