[codered]

Well to start I dont own a sut but a suv h2 but can give some pointers. All the engine mods will do just fine on the h2. Now with supercharging you'll be alright, but down the road with any other car all that power going through the drivetrain will cause things to go bad faster than usual because of the stress it puts on it.
Spare tire they have kits to remove the spare tire. If you do this you will have no where to put it.
The flares you can find at several after market websites including somo i believe.
If you get a sut with air ride you will have a problem putting wider tires on because it will screw with the air sensors on the back wheel and has been know to break them if you have a tire wider than 12.5. the biggest tire you can fit stock with out doing a lift is 37x12.5.

As far as room with the sut is about the same with the suv. You have to fold the seats down in the suv just like the sut. You just dont have a truck bed.

Hope this helps!