Dude, good on you for having the resolve to play in the tourney. I think before you play there though, get some practice playing real money online MTTs, you won't learn very much from the freeroll tourneys because a) people dont take it seriously enough and b) the quality of the opposition is generally poor; playing against tough competition makes you tough.

Also, almost all experienced players will never advocate folding aces preflop (except in very very exceptional bubble circumstances). If you get it all in with aa preflop then you have done a good job and if someone sucks out on you so be it.

Good Luck at the tourney.