Ok, I'm a bit lost in some of these hands, so I guess I should try to come up with an answer myself.

Hand 1)
Pre-flop: I don't hate the pre-flop limp, but I wouldn't hate a fold either. I'd probably fold.
Flop: Value-bet - fine.
Turn: Straights and flushes are complete (and possible holdings). There could be lower two-pair hands or AsXx hands still in there, but I don't mind going for pot control here with a check behind. I don't think I'm ahead often enough for outright value.
River: As played - I think we're behind and I fold. He is clearly expecting a call and he knows there are straights and flushes on the board. Had we checked turn I'd be happy to see a showdown for a bet up to $2.

Hand 2)
Pre-flop: I'd raise to $0.70 here. Even if your caller is UTG that bet size gives a perfect SPR for the kind of hand you are looking to make.
Flop: Fine - the low donk bet could be designed to give himself good odds on continuing with a draw or an otherwise vulnerable hand (mid pair).
Turn: $4.4 has gone in and we have $5.6 behind - it's a commitment decision so we need to decide whether to put in $5.6 more to win a total pot of $20.95 - we need to win 26.7% of the time or more for all-in here to be profitable on showdown alone.
Against a range of TT,77,QTs,Q7s,J9s,T7s,98s,QTo,Q7o,J9o,T7o,98o we have 21.3% equity. The flop bet size indicates that we're more likely to be up against J9 or 98 type hands - and the turn min-bet indicates the opposite (set/two-pair or a J9 hand that hit). Or KJ on flop now that I think of it. If I include KJ in the above range our equity jumps to 33.9%. But I think I can safely discount KJ as the turn min-raise is not at all consistent with that hand. Still, KJ could have become a 'missed draw turned bluff on scare card' hand.
If we include some air and some fold equity in our considerations an all-in move goes to very marginally +EV. And I guess if we're close to 0 EV we want to play because it makes our image worse.

Hand 3)
Pre-flop: Fine
Flop: Flop hits villain range well. I'd consider just taking the free card and maybe improve to beat him for free.
Turn: (as played) time to slow down - no reason to bloat the pot here.
River: (as played) You've shown nothing but strength throughout the hand and still he leads. The question is if it's a "let me get away with a cheap showdown" play or a "oh I'm so weak, raise me so I can crush you" play. Probably the former, and in a sense this play is more weak than just checking. Despite that I'm not sure there is a bet size he's folding. I think it's weak in a sense that he'd hate to have to call another bet - but would call it anyway thinking it a poor play. I would not be surprised to see the villain show up with T9 or something similar. On the river as played I'd call the weak lead and expect to lose almost always. If you want to try to blow him off his TPWK hand I think a bet around $5 is as likely as any to succeed.

Hand 4)
Pre-flop: I don't mind a call - I also don't mind a squeeze.
Flop: SB is donking - either drawing to a worse flush or on a set. Overpairs should bet a bit bigger but not impossible. UTG plays like he has a strong overpair like QQ-KK maybe with a spade for a backdoor draw for added equity. The raise size is only an overbet by $0.10. If you're up against exactly KsKx, QsQx (blockers) you have 43.5% equity. That's pretty exactly the amount of time we need to win for calling an all-in to be profitable. Add in the chance that UTG is on a bluff and shoving all-in is clearly profitable.
The flop call I'm ok with not because I expect a squeeze, but because the hand I'm looking to make (a flush) is likely to be best multiway - with more people in the hand I'd just get more value out of it. That said, raising here is also not wrong.