J7o complete

I would fold pre and limp J8o+ if the big blind's a fish. If he's a TAG, you should raise, against sticky TAG or LAG you wanna raise tighter

The turn bet is close, I think you could c/c turn - c/f river and hope that he'll check back a better hand on the turn. The bet is ok though. I like the c/f on the river as well, the 9 is just such a bad card

Preflop fold yes. J8 is supposed to be the bottom hand you should complete with, after one limper. but since he limped from UTG and may have a strong hand, i would rather take JT. once utg called this flop he will always have something on the turn. i doubt he will fold a better hand, he won't even fold QT or something as he does still have a gutshot. but he may check back with Qx Kx and you may face a raise on your bet. it's not a crucial mistake as you does have a lot of outs but check/call Turn is better and on the River you can check/fold as taavi already mentioned.

postflop looks pretty ok to me.

bet or x/c turn are close at first glance.

He might check back better hands like 88-JJ, Qx or better 7x which is good.. we probably don't get Qx to fold if we bet turn... and our bet is as a semi-bluff and for protection against loose flop peels/ picked up draws.

That said, our draw is nearly the best one available and so protection is less important.

Yeah, check/call turn is much better than bet, but i doubt betting would be a big mistake on its own... but compared to x/c I think theres a significant advantage to checking the turn.