Hand #1: If you want opp to fold QQ-JJ to the river bet, you need to bet around 3.5-4
Hand #2: For me this depends on players stats/reads.
Hand #3: OK, this way you'll make AQ/AJ pay you. Why not 3bet PF?, then if you hit your A, you can get all-in.
Hand #4: I'm maybe too nit, but I'm check-calling here, you are only beating a pair of Kings.
Hand #5: Bet more flop (i.e. $3), with so many callers, you need to make them pay on that drawy board. As played turn is difficult you're ahead of AA/KK/88/AKss and behind QQ/JJ/AK/99. I think I call here. If you had bet $3 on flop, the pot would be $9.25 and if you bet around $8 on turn you would not have any problem calling any raise from villain as the pot would be too big.