Hand 1:
Fold preflop. but since you called, the flop was nice. I think its ok to bet out the flop and turn b/c you have pot odds with 1-2 opps calling behind. 1 to 9.5 on the flop and 2 to 11.5 on the turn. Although, if you get raised, you dont have pot odds any longer. So its a trade-off between being the agressor (all opps might fold) or securing pot odds on flop and turn. You still might be worried with the flush draw taking some outs away

Hand 2:
I might check the river. With so many callers, its very likely someone made a flush or straight.

Hand 3:
I might cap the flop. At least the bet on the turn from UTG would be convincing of set or better. Since Ace dropped, if UTG had QQ or JJ in same scenario, UTG just might call the turn if you capped the flop and you would have more information vs calling the 3-bet.