Long exposure – use low iso film such as iso 100 (as it helps avoid reciprocity failure).
Flash – use whatever depending on how much of the scene you want lit, I use fill-in and 100 iso as this avoids overexposed areas that can't be brought back.
Outside with streetlights etc. Then you want a fast film, maybe.
I'm sorry to hear that.
Night time photography:
Two out of three means I win.
:)