You can go to the Met Opera website right now to see tickets available. Last year I helped people visiting get Met tickets I think it was New Years ever for face (perhaps it was one day before New Years eve, on the 30th, I don't exactly recall). Broadway, again, there will be tickets. When you arrive buy New York (
NOT the Newyorker - but New York) magazine, has everything listed, reviews, restaurants, events etc. NY is a wonderful place to visit as long as you use common sense, don't wander around or take the subway very drunk at 3am etc. (same applies for Chicago methinks).
New York Magazine obsessively chronicles the ideas, people, and cultural events that are forever reshaping our world.
nymag.com