Read Harrington on Holdem Volume 2.......seriously it's worth the 20 bucks you'll pay for it, he's helped everyone who's read it's tournament game tremendously
10x BB is a good limit where you are pushing all in with any raise.... it doesn't mean you have to start pushing with any Ace any pair etc just yet... but if you raise 3x BB, you pretty much committ yourself to the hand so you may as well push and get fold equity
Your 'M' value (as explained in Harrington on Hold Em Vol 2) is another good way of looking at this. Your 'M' basically is a number of how many rounds you have until you are blinded out.
The best advice is BE THE ONE PUSHING. Do not CALL all in with out an EXTREMELY strong hand...even fold the best hand a few times if necessary...if you are pushing a few times uncalled, when the blinds start to really get up there, blind stealing 2-3 times is equiv. to a double up... and remember when your pushing you have 2 ways to win, by showing down the best hand or by getting everyone to fold... if you call you only have 1 way.
Harrington explains the first in rule... meaning when you have a low M (or low BBx amount) it is just as if not more important that you are the first on e entering the pot, than what your actual cards are. In fact there are many situations you should push with hands such as 95o (or any two cards) if you are first in and short, hoping to pick up blinds or if not have two live cards and be in a 60/40.
Remember in large tournaments you have to get lucky as well...
Perhaps our tournament experts ( TP, BDawg ) (Mayhem I'll include you next time for your 180 cash
) can add some more light
Edit: Apparently TP posted as I was posting... now lets see if he had anything good to say
Edit 2: As for your last question about trouble hands in the BB... I like to mix it up, and its most table dependant. If you are in the BB with K10o, you need to know your players...say there are 2 limpers, the SB and you. Will these limpers limp with hands such as KQo, QJs. KJs, AJo etc? Or would they open with these hands? If you raise how likely are you to take the pot down right there... if you are likely to take it down 2 out of 3 times, Im raising in this spot (and with any two cards also at times), ESPECIALLY if you are liekly to take the pot down with a CB bet the one time you do receive a caller.... while SHORT STACKED however it becomes a bit more difficult...I'd still raise if I think it'll take it down, but Id be overall less aggressive as you dont have room for error..... this may be a more aggressive approach than some other people like though...