You pay for your food and drink on the flight, it's not provided free of charge.
Baggage is also extra, so keep it down to 20kg for your suitcase you check in, otherwise they'll charge you extra.
I think 10kg is the maximum weight per person for hand luggage.
If you are exceptionally tall, check in early and get a seat in front, because there's not much leg room. No extra charge for booking your seat in advance, unlike Ryanair.
No smoking on Aer Lingus, don't even try it in the toilet.
And get yourself to the airport in good time, to allow for the security checks that are in place at EVERY airport now.
Not sure if there are direct Aer Lingus flights from Paris to Boston, but I suppose you want a stopover somewhere in Ireland, right?