I think the fourth hand is the only one that's really a tough decision and the other three hands are standard.

Hand 1: Bet at least $7 on the flop, and why do you think such a loose passive player wouldn't have "stuck around" with a flush draw for only $5? Of course he would have! That being said, there are a ton of hands he could have that you're still way ahead of. Make a bigger bet on the turn and go all-in on the river.

Hand 2: If you get more than 10% of the effective stacks in pre-flop I don't even worry about going broke with AK. I think you played this hand fine except that I would call if he shoved a blank river.

Hand 3: Easy fold against this type of player, and of course you have to bet the flop, because this guy will be calling with tons of hands that you're ahead of.

Hand 4: Really depends on your reads. Have you been winning a lot of pots lately and people might be waiting to play back at you? Honestly people do this stupid little check-min-raise with sets, top pair, middle pair, air, you name it. I usually give them the benefit of the doubt the first time I see them do it, but if I see them do it too often then there's no way I'm folding here.

PS: If you can keep finding tables full of opponents as terrible as these guys, you'll do very well at 50NL.