Aer Lingus will
not check your bag through to
IST. They don't have an interline agreement with
TK and will no longer check bags through unless you have a through ticket. I'd say give yourself at least 3 hours to transfer in
LHR.
You will have to go through immigration at
DUB. When you reach the baggage hall, follow the signs for connections. This map here should give you a better idea: (you'll arrive at Pier B)
If you intend buying duty-free drink on board from
JFK-
DUB, remember you won't be able to take it on your connecting flight to
LHR. It'll be taken from you at security screening in
DUB. A trap a lot of people fall into
You've chosen a nice routing!