It's a little tricky because with size 7 boot you will I think need a medium binding.
So burton feather 140 for instance would fit your weight but only takes a small binding not sure if this is strictly true - if you can squeeze a medium binding on there (get advice from a shop/dealer about this) the it would be a good choice, easy board to learn on. Burton Deja Vu or Lipstick will fit a medium binding at 141 cm length which would work but you're at the bottom end of the weight range.
Buy used to save dough.
Freeride or freestyle won't matter much if youre just learning, freeride is the better choice but not by much.
A cambered board will discipline your riding style but you'll catch edges a bit more, while a hybrid or rocker board will turn easier and catch edges less so it's a little easier to learn on. Where do you ride - some people here in the east coast prefer camber b/c the other profiles don't handle ice as well - many places out west there's less ice so this is less of an issue.