Hand1: Looks like flop is scary for both of you. AA may have put you all in pre flop. Would he slowplay AK, AQ or QQ ? Or is it more likely he has KQ or JJ or worse. Think I would bet 2/3 the pot.

Hand2: Most likely he is on a draw and he is hoping you are on AK and will fold to his raise. If he had an 8 or 77 would he have raised ? or would he have called ? I would re-raise.

Hand3: Checking the flop has put you in a difficult situation. It is now going to cost a lot more to find out if you are beat. He limped in then called a big raise pf, smells like a pocket pair. Without a read I fold.