first suggestion would be the head gasket which Montana's are notorious for having problems with, followed closely by a crack in your cylinder head or engine block
The gas tank in my extended 2000 Pontiac Montana is 25 gallons. I would imagine the 02 is the same.
A common problem with the Montana is the power steering pump.
well you can change the entire rear hatch with that of a trans am's but I dont think it would be worth the the money to convert the car into a trans am style car.
the steering wheel..
Possible starter or starter solinoid? more info would help
The support pistons need to be replaced.
NO! the Montana is a front wheel drive minivan and the firebird is a rear wheel drive, even if they were both rear wheel drive for some reason, the firebird engine would shred the wimpy minivan trans and it would be just wrong to put a minivan trans in a firebird.
if the vin codes match then they should but i'd look at the wiring diagrams to be sure...
try not stealing a car.
the flasher located on the fuse block is more than likely burnt out
check the cabin filters inside the glove box, if theyre clogged that will cause low heat it happened to my wifes 2000 silhouette