So I don't have a lot of hands on this villain (27). He plays 24/24, with a 3b% of 17. I know data isn't representative, but I saw this as a fine spot to 3b, since his stats were to the looser side. This might've been my first mistake?

OTF: I flop 2 pair on a super dry board and elect to cbet around half pot. I think I do this with most of my 3b range, except very SDV stable holdings like JJ,QQ,KK. He calls, so I put him on something like ATs-AKo, maybe occasional A2-A5s, but I block these hands, which makes it less likely that he has them.He of course has 3 combos of 77, but I find it as likely that he floats with 88-JJ and occasionally QQ+KK (unsure if he always 4b these holdings OOP). I don't think he has 22-55 since they would've most likely folded pre.

OTT: The turn comes an offsuit 5c, which I don't think hits his range very hard. Only A5s IMO. Since he still has a lot of other Ax and middle pairs in his range, I think this is a good spot to go for value. I bet around 2/3 pot, hoping to get called by AT-AK or 88-KK. When he decides to raise almost 3,5x I find myself kind of lost. I don't want to GII and scare away bluffs, but I just can't seem to find that many bluffs here? I struggle to even find one combo. Anyhow, I just think my hand is too strong to let go, given this dry board which is why I elect to just call here.

A few questions summed up:
1. When I choose to 3b with semi-bluff hands, should I go for a different sizing?
2. My flop and bet sizings - go bigger or smaller?
3. Should I just have folded turn, if I plan to fold to river bricks anyways?
4. WWYD on the river? Am I just too far up in my range, so that I have to call?

Opinions? Thanks!