Hand1: With QQ you want to thin the field to hopefully one caller, the raise amount that accomplishes that depends on the specific table, but you may have raised a little too little preflop.
On the flop you got a pretty good board in the sense that there is no A,K or mid-high paired board, but it is still a dangerous board with decent str8 and flush draws. flush draw is much more likely then str8.
With 5 people seeing the flop you need to deny pot odds for draws, the pot is 100, I would bet at least 100. I want to end the hand right here.
The turn is a tricky card for you, if someone called with a flush draw you are way behind, but you cannot let someone get a free card, so push and hope that nobody has a flsuh made.

Hand#2 I think you played it fine, except for the river bet, I would just check the river

Hand#3 - 5 people seeing the flop without a PFR means you are facing pretty random hands, you need to bet enough on the flop so that only someone who has a piece of the flop will stick around, the amount depends on the specific table, but apperntly 20 was waaaay to little.
The turn is where you blew it on technicalility, I dont think AI is the correct move, since your stack is significally larger then the pot, I would bet agressively, probably in the 200-300 area