Especially New York, and also other touristy places, where almost every other person is holding a camera are great for hassle free shooting, especially people. New Yorkers are certainly used to it. With a bit of common sense you should be able to get good pictures without being hassled, of course it depends on your style. Shooting like Bruce Gilden is not for the faint of heart (check youtube if you don't know him). A tripod might be problematic during rush hour on busy sidewalks though.
If I were you I would invest in fast film, you will be shooting in the shade a lot. Enjoy your trip!

ps: I would assume that film is cheaper at B&H Photo in NYC than in England, plus you don't have to haul it there...