(1) I'd reload to 100bb preflop
(2) Limping Behind and calling raise is fine.
(3) As stated, I'd open fold if UTG hadn't have limped
(4) Calling flop is pretty bad, as you have relatively little equity when behind [2 outs to a set], and when you are ahead you aren't ahead by a lot as most hands have 6+ outs against you.