3/6 Live. I'm rusty on limit Hold'em.

[Biggle10]

#1: 2 limpers. Hero limps A6s. Button calls. SB folds. BB checks.
Flop is A76 rainbow. Checked to hero. Hero bets. Button calls (Loose passive. I've seen him call down with bottom pair frequently). BB calls (drunk off-duty dealer). Turn is Q. Check. Hero bets. Button calls. Blind check-raises.

#2. Lag raises. Unknown calls. Another lag calls. Hero calls in SB with ATs (meh). Flop is AT6 rainbow. Hero leads. Lag 1 folds. Unknown calls. Lag 2 folds. Turn is 7 which puts 2 clubs on board. Hero leads. Unknown raises. If I 3-bet, what is my plan if villain caps? If I call, what's my river plan. Is there ever reason to fold?