limit bubble play

[unformed]

i'm playing $10 PP limit tourneys. I can generally make the top 5 without a problem, simply by playing really tight, but it's when it gets to the bubble that i seem to have problems. I've got many finishes in 4th and 5th. The ones in 6-10th are usually where my stack size was killed by a bad beat

Anyways, reaplying the games where I finished first I'm noticing my aggression level is much higher in the bubble, ie: raising middle pairs after the flop, etc. I'm wondering if this is correct?

What hands should I be raising PF with in Levels 4+ with 4-6 players? (I figure any pocket pair 77+, AK,AQ, AJ, At)

What about on the flop?
If I'm on the button and I've got JT. The flop is KJ4. It's heads-up and the other guys bets, so I call, raise, or fold? I've noticed many times that if I simply raise, the other guy often folds. I don't like calling, since I've read that bubble play shoudl be either raise or fold (except in certain circumstances). I don't mind folding, but then I tend to think I'm being outplayed.

I realize that if I'm in the top 3 stacks with a bit of a difference from the next one, I can probably play very tight until I'm ITM, but it's my bubble short- and mid-stacked playing that's killing me.