[Kalledrengen]

If have seen him bet a lot of flops and turns I think calling here on the flop is a decent play to extract a bit more value. The flop seems somewhat harmless. I do however think you should really raise him on the turn.

You ask if you should fold the river.. Not sure. A LOT of opponent uses a PSB river bet as their standard weapon to take down pots.. I guess this depends a bit how loose you feel his preflop calling range is when OOP.
I tend to call such bets with tPgK when the opponent seems wild and crazy.