Is 155 size snowboard pushing it?

it wouldn't affect your riding unless theres lots of powder. If your on a 155 and run into powder your gonna have a hard time plowin' through it. I'd say stick to between a 158-162. maybe something like 160 for both park and freestyling.

Depends on the board really, but that'll be a little big for you, I'm 6 ft and 165 lbs, and for park I ride a 154 or a 156. If you expect to grow into it and don't wanna keep buying boards cuz they're pretty expensive a 155 wouldn't be bad, just depends where you're gunna end at. If you hit like 5'11 or 6 ft, and are only 140 then that board will still be hard to torque/rotate, so you'd have to put on some weight.

Uhh, yeah. Without your freestyle leanings, a good size for you would be around 167-168. For park, I would recommend a 162.

Trust me, I'm 5'9" and 180 and I ride a 154.5 for park, there's no way that board would work for you. First of all you wouldn't be able to go very fast, and if you hit anything like powder you would sink all the way to the bottom. You need way more surface area than that.