Ok, here's some advice from a NYer ...
When: NYC is great at any given time. Depends upon your style ... If it's shopping, you want be here in late November/ early December. If you want to  go around & see stuff, be here before mid-Oct. 
Hotel: Get a room in a decent hotel in the city - it'll save you a lot of time. I'd recommend the Marquee Marriott in Times Sq. Fuck the $, you'll be in the middle of everything, never have to travel very far, etc. DON'T stay in jersey / queens. Simply not worth the headache
Getting around: Subway during the day - get a $5 NYC map and you'll be set. If you plan on taking the subway around - get a Metro pass. Take cabs at night since they'll be faster at that time. Alternatively, walk ... it's a great way to see stuff. You blink in NYC and you'll miss something. To get from east/west, use the cross-town bus if you don't like to walk.
Dining: Avoid the tourist traps! The tourist traps are the ones that advertise a lot, have people at the door ushering you in & the interior is usually large. They're really not worth it. Here's what I'd advise - eat cheap most of the time, splurge on a few meals at a few classy restaurants. NYC has some of the most amazing & expensive restaurants in the world. And here's another piece of advice - TIP WELL! Most euros, esp. brits are really notoriously bad tippers. In NYC, 20% is the standard tip. Don't gyp off your waiter/waitress unless they're been rude or something. 
Airport: Depends on your baggage. I prefer JFK / LGA. It's a standard $50 from JFK to anywhere in NYC by cab. JFK is also connected to NYC by the subway but the wait times can be long. 
Clubbing / Drinking: All over the place - from high class to all out kinky, whatever you want - you'll have to be more specific. Covers range from $10 - $200 and oh yeh, don't forget to bring your id. Drinking gets expensive fast in NYC & most bars have a minimum charge if you want to start a tab.
I'd be happy to answer any questions ...