1. Download the cycling map of NYC
here. Please stay off of Houston Street...would prefer not to hear about another cyclist dead. Riding in NYC traffic is a thrill, if you play it safe and don't do anything stupid.
2. Hot and humid.
3. Depends on what you consider a "hill"; there's nothing steep in Manhattan...but it's not all pancake flat by any means
Also, for a candid appreciation of the obstacles of NYC riding:
http://bikesnobnyc.blogspot.com/2007...our-enemy.html