Call because good odds ? Or fold because we are often beaten ?

For starters I would open with 3BB from CO. no need to go bigger.
I would raise his donkbet OTF. We have only middle pair, we need info and we can rep an overpair.
I don't see much value in calling, we might already been beat or up aganst a strong draw.
If he calls the raise I'm done with the hand.

OTT, I would check behind. we have showdown value

River is a fold for me

For starters I would open with 3BB from CO.

I think as a standard we could bet even 2.5bb. But here we seem to have a lot of recreational players behind so opening bigger might be justified.

I would raise his donkbet OTF. We have only middle pair, we need info and we can rep an overpair.

I think it is bad to get induced by his donkbet and start raising with hands that would normally be really bad raises. We have small chances to improve if we are behind. We can't raise purely for value. And raising just for info is not good. We can just call here and probably call many turns too and hope he slows down OTR.

OTT, I would check behind.

This type of villain can donk the flop with a wide range. By betting we might be able to fold out some trash that still has equity against us and also get some calls from weaker hands and draws. With a bet we also might buy ourselves a free showdown.

River is a fold for me

I agree with this. Villains line looks strong and I think this river donk is very rarely a bluff. We can fold here.