77 - preflop fine. Flop and calling or raising are both ok - i think raising is better cos otherwise you'll struggle for value against AJ+ if the turn is a heart. Depends on levels etc, raise 75%/call 25% is good here. Turn is all good, obviously call his 3b.

AK - meh, ya gotta do what ya gotta do. Fold pre is ok without reads, shove is obviously fine as well vs a 75bb weirdo-stack

55 - pretty loose utg, but definitely ok. Do you prefer opening KQs or 44 from utg? QTs? nh.