Call me a nit but I'm folding the flop. Board is dry and vs an unknown I'm just letting this go for now.

I think you need to make your decision on an earlier street than the river (for me, if I'm calling the flop, I'm more than likely calling down), if you've decided to call down, call. Most opponents, in my experience, wouldn't be going for 3 streets here without a hand weaker than TPTK, It's pretty much a "way ahead, way behind" situation, and I'm kind of only scared of 22, 44 and random 2 pair combos.

Against this guy I´m not sure if opening preflop is the best idea at all.

But then again you only have 12 hands overall? Flop is probably not the worst call but it wouldn´t be the worst fold either.

On the turn I´d just muck it. Flop contains no draws besides 53 and A3 and A3 got there, 53 has some equity and will most likely barrel the river - while you´re still beaten by almost "any" J, sets and 2-pairs.

Yeah, the decision should be made on the flop, especially since it dry. I would fold flop - just remember he raise the flop like this (many regs would just call sets here), and keep on watching him.  I don;t think it's a good idea to make the alldown in the beginning of the session with him and with no information from previous days

I would check back the flop a decent amount of the time but given the dry nature of the board we shouldn't expect to get check raised a ton so betting isn't the worst thing in the world. As you continue to face bets in the hand your range should be narrowing so either you're not doing that in this instance or your flop bet/calling range is way too wide.