Wow - too many questions.
#1 - don't know
#2 - the same filter as the 2000/01 fits the 2002, I sell both AMSOIL and K&N at a great price at www.imprezars.com/products.htm
- they allow the car to breath in more air and make more power, and in the long runs are cheaper to maintain than a disposable paper filter.
#3 through #5 - duh... I need to crawl under an RS at the dealership...
#6 - everyone who has tried Kumho Ecsta and has tried my RE730's feels the RE730 stick better. They are under $110 each from www.tirerack.com
but I go a local firestone dealer to price match them for me.
#7 - Intakes - you didn't ask about this, but it looks like the Version 5 GanzFlow will fit!
I played with one at the local dealership this week. The 2002 RS has a wiring harness running inside the front hole in the inner fender where the intake goes, which can be lifted out of the way so the intake can go into the hole past the wires. Just don't push the edge of the intake's opening against the wires, it needs to go past the wires so they are off to the side of the intake as it goes into the inner fender.