what plane should i use to beat level twelve and what speacial weapon?

if level 12's the level with the huge rail gun (I don't remember anymore) then the best
plane to use is probably the F-22 with it's air-ground missles. If you don't have the
F-22, then that ****s... but probably the F-15 or something that's manueverable with
air-ground missles (or lock on bombs, bombs that don't lock on won't really work). While
you're playing, don't worry about the planes, they won't do anything too bad to you, just
make sure you're always at full throtle and do a couple high-g's every now and then. And
then just shoot the targets whenever you get the chance.

So far I've beaten the level 2 times (1 easy, 1 normal) and died once, so it's worked for
me so far.

Hope that helps.