3b pot OOP, flopped 2nd nuts

I'd likely fold pre-flop, this is a pretty trashy hand to 3-bet OOP.

As played, I think your play is fine. You can't fold for a small bet on T or R in a 3-bet pot.

I like checking this flop to induce bluffs and make villain think we haven't hit this flop.

You 3 bet preflop so you can rep a big pair here (which would never bet this flop) and check. When you do bet this flop you are isolating yourself against flush draws, sets and nut straights and his raising range is going to be even tighter typically so you could well find a fold if you think villain would just call with a flush draw and possibly raise a set/straight.

I think you could possibly find a fold on the river here. If villain had a straight I would expect him to check a lot of rivers here, it does look like a value bet from a super weak full house. That said you need a read on your opponent to make a fold.

I don't see why we would take a c/c line against such a passive fish. His betting range is most likely a lot stronger than his calling range from my experience. If we c/c the flop what is our turn line?

I think a b/f flop + turn line is better, he can definitely call with twopairs, pair+draws and if he raises it's the nuts. We can probably then safely c/f the river expecting to get a free showdown whenever we are good.

I didn't expect the fish to overcall tough. He's playing at 64/10 on a small sample, and looks quite the station.

Sick contradiction.

I like 3-bet vs nitty player. Always expect to get called by 64/10 to my left. As played - vastly depends on villain's flop/turn/river aggression. Passive preflop players are not necessary passive postflop, some PLO players play a vast passive range pre and try to outplay postflop by being aggressive. I would take your line vs aggressive player and fold river vs passive player.