Work: as foreigners you'd either need work visas (very hard to get) or work illegally. Electricians need to be licensed here and you won't be. It would help if you had a local contact, there is a fair amount of illegal Irish working in Boston all the time.
Gigs: relatively hard as there are lots of bands here and most venues book out at least 3 months. A local contact who could set you up some gigs before you arrive would be needed. There are dozens of pubs here owned by Irishmen that would be the place to start looking.
Housing: expensive, especially if just for the summer. You might be able to sublet from some students who will be out of town.
Renting Amp's/Pa: just buy some when you get here and sell when leaving. That will be
much cheaper than renting. There's plenty of places to get used gear here for low $$$ and a fair number of clubs have PAs installed so you can probably get by with guitar amps and drums. Get small stuff easy to carry onto the subways or load into taxicabs.
Your best bet overall would be to get in touch with anyone you can here in the area willing to help you out. Start now, it'll take months to get anything lined up for next summer.
BTW I remember Rubyhorse, they came over and did a summer residency in a club called
the Burren where I used to play quite a bit.