I'd say that they're pretty similar apart from being 4cm different in length. LOL
Nah dude, it's powder board. Go 156. 156 will still be plenty maneuverable and playful.
I'm usually in the 175-180 range (currently 200, but getting my sorry ass back into shape) and my powder stick is a 164.
You're bigger than Jeremy. That's him pictured with me in my avatar pic. He's in the 5'8" range and I'd be surprised if he's a pound over 150 - in other words, about the same size as most pro riders.