in hand one it seem like MP1 has hit his set. good pfr and flop raise. i call down here most of the time.

hand 2 is deffinantly too passive. in an unraised pot you need to bet out on this flop. read ed miller's post.

hand 3 is fine. you should only play small pp's for their set value. you should fold when u miss, especially when ur hand becomes an underpair to the board