1) Fold. In a limped pot anything is possible. Flush, Straight, Set, Plus any 2Pair beats you.

2) Fold. There's no need to get your stack in here. You don't even have TPTK.

3) Fold. Don't bet the river. Why are you calling the flop? I hope it's not just to draw to a gutshot.

4) Well he is obviously not drawing. That board is really dry. If I've seen him do this crap often I'd think about calling.

5) Well I don't like this spot at all, but I guess you have to call here. When you get c/r'd you have to decide right then what you want to do with the hand. You shouldn't re-raise unless you want to get all-in.