Grunch:

Hand 1: Call is ok. If your read is this guy is a passive, then I could fold since the pot is small, w/o a read I call and add a not that this guy draws to gutshot str8.

Hand 2: You have to raise preflop as I am sure other replies are saying. Calling on the river with such a small pot and UTG+1 wakes up totally depends on reads. Pot is small, and I've folded in this spot against passives many times.

Hand 3: I waffle on the flop on this hand. Against Tight Passives I like to bet out, against the LAGtard I think I'm c/f more often than not when I miss the flop. Not saying this is the right thing to do, just what I do.

Hand 4: I like every play but the River. Villian may have trips, but he could be on a A8 or K8. Might be a spew on my part, but I bet this street too.