I am writing a novel set in NYC and I need more information...?

I am from North Carolina and I've never been to NYC before. I only know what is shown on television. So I need to know about any forums, maps of the city online, or any information that can help me capture the feel, sight, smell, essence of NYC. For example, what are the affluent areas, what are the slums? What about nightlife? The cost of living and simple things like food, movies, etc. NYC slang would also be good.