1.

Check-call the turn, generally check-call the river. As played, I'd fold the river without a read. From my experience, most of the time when they goes all in on that board has a flush. If he can do it with air, good for him.

2.

Check-call is probably best. Problem with a bet/fold line is that hands you best like AQ, 87, J8, might raise and you lose a lot of value if you fold incorrectly. So well played

3.

OMG what are we waiting for!? I'm super conservative with TPTK but even at higher stakes I instacall. Note: stack sizes + pot odds (2:1 odds - only have to win 33% of the time) + draw laden board + 25NL. If you have a read that villain is sensible/tightish then call the flop and let your position do the work

4.

Not mad on the turn raise. Calling seem like a good option. $5 on the river looks sensible.