Mini-step 5 advice

[DoomSlice]

So I basically just jumped into the STT scene without reading this forum or practicing on the lower level buyins, hopping right into the 30+3s and doing relatively well.

However, on the side I've been trying to advance through Party Poker's MiniStep tournaments, starting at level 1 and working my way up. It took about 3 tries to reach level 2, but after that it was smooth sailing up the steps. Unfortunately, I feel like I've never really gotten a hold on tournament strategy, except for exploiting bubble play. What I did notice was that step 4 was much harder than the other steps. At level 6 there were only 2 people out, which in all of the other steps would have meant that we would be down to 4 or 5.

So basically, does anyone have any general nuggets of advice about:
1) restealing (something that I have hardly done at all)
2) open pushing air (why not make a standard raise?)
3) defending your blinds against possible steals (even with mediocre hands)

Thanks!