Actually looks to me like he's flying 1/2 way around the world... Shit man that's quite a journey.
I've been to NYC many times & always have a great time. Lots to see & even more to do. The summer would be better for the attractions, but winter is cool also.
In regards to shows I'd check out pollstar for NYC. They list lots of shows for most of the venues.
The wintertime tends to be a popular time for metal acts, so you should be in luck.
As for the weather, yeah it's gonna be cold. Expect average high temps around 0-5 Celcius & lows down to -10 or so. I'm also sure you'll see snow at some point.
Try to visit Boston if you can. No shortage of places to party if that's your thing. I'd recommend Lansdowne street, Faneuil Hall, & Harvard square in Cambridge. All great areas with lots of cool bars & clubs. Cambridge is your best bet for music. Not much metal in Boston itself, but still lots of fun.
Good luck man & enjoy