If you haven't seen "In The Heights", you MUST - MUST - MUST! It's fantastic - and I don't even care for Latin rhythms! Great dancing, marvelous cast, and an actual decent plot besides! Go to the TKTS shop in Times Square and see what you can get for that night; there's always something worth seeing and the tickets are usually around half-price. The only show I've paid full price for was "The Lion King" which was worth every cent, BTW. If it's small, intimate classic theatre you're looking for, try "The Fantastic" - one of the the longest running musicals in the world. Tiny theatre, small cast and you feel as if you're part of the show.
The subway cards are good to have and there's always someone around who can explain how to get where you want to go on them. Avoid cabs if you can; they're slow and expensive.
And I'll second the hop on-hop off bus tours for a general orientation of the city. The NBC Studios Tour was fun and educational.
I can't say I've ever had a bad meal in NYC. We usually just read menus until we find some little place we like and give it a try. My friend swears by Johnnie's Pizza but be haven't managed to hit it yet. There are tons of places so it's an adventure in eating...
For shopping, if you're adventurous and don't mind knock-offs, find a street fair or head to Canal Street. It's worth seeing even if you don't buy anything; you can learn to spot the knock-offs purses and jewelry if nothing else. And it's a great place to buy that extra bag you might need to haul home your more pricy finds.