67s, FD+pair, river flush

Is 4x your standard open there?
OTF is ok.
OTT I guess you have enough equity to call there with your hand but I wouldn't hate folding. Actually at the micros I think it would be ok to overfold vs turn and river raises.

OTR I might just call. What hands can villain raise on the turn? Probably not any Ax hands and since he didn't 3bet pre he pretty much won't have AQ. 66 should have raised already OTF. So it leaves 33, slowplayed 66 and a semibluff with a draw. If he was on a draw you are probably behind OTR. I would call there but I would not shove.

I think it´s ok. As lassi pointed out preflop sizing, I recommend bigger sizing from early position (3,5-4x) and from late smaller (2,5-3x). Flop is cool. OTT I would probably keep the sizing from the flop and bet again about 2/3 of the pot. I believe folding OTT is better. When we hit our flush, all in is the right decision.

I suppose you open 4bb from all positions as a basic strategy.
I think Lassi and Mossek have covered all streets.
I agree that calling a x/r on the turn at this level is too loose.

Other considerations set aside, turn is easy to analyze, but things are close. You get 46:16.5 ~ 3:1. If you can make another 35 bb on average when hitting, it is a mathematical call. I think you can, but it is close.

Raise river? Playing safe would be to just call. But I think he'll be forced to call a raise with most hands he raised turn with for value, due to pot odds. Him having a better flush should be rare due to action on previous streets. K♣:J♣:/J♣:T♣: and similar might be there, sure, but there are more :Ax::Qx: and :3x::3x: that will look you up. True, some AQ might 3-bet pre, but don't rule it out. Close, but I approve of the raise. Have you had more money, a river raise is a no-no.

Thanks for you answers guys! And yes, 4bb is my standard open raise (because of basic pokerstrategy articles). Do you think it makes sense to raise smaller at NL2?

Well that depends. I'm not sure why it tells to open 4bb but I guess it is because it might be easier for beginners to play with very tight ranges and that way you might make the most money when you hit?
Anyway the usual standard open size would be 3bb and from BTN and SB maybe even less. But nowadays you'll see all kinds of bet sizings from all positions, some open less than 3bb as standard.