Hand 1: Check the river every single time. No hand you beat will ever call. (Not 4 card straight to an A) and you have to fold to a raise.

Hand 2: If you raise preflop, you'd likely just take down the pot and it'd be very risky to call his lead. Fine as played.

Hand 3: That's tough. Very difficult. The only hands that make any sense are bluffs, 22, or 44 (possibly KT). Reads would be very, very important here. Is he the type that plays every pot? If so, he might think that KQ/KJ is good here. If you're going to call the turn, you might as well push, given that you're calling any bet on the river anyways. At least put some pressure on your opponent.

Hand 4: Raise is fine (though aggressive) should fold to a reraise preflop. Likely dominated. Fine as played, (sorry about the bad beat, at least you got your $ in while ahead).

Hand 5: Very well played. (representing 2 pair).