1) are the Subs 4ohm coils or 2 ohm coils?
2) A good amp that i like is the sony 225x2 xplod from like 1-2 years ago. it's stable down to 1400x1 at one ohm, and sounds great. If the subs are dual 2 ohm, you would get 225 watts a channel, and if they are dual 4 ohm, wired in parallel you will get, i think, 600x2. The RF you mentioned would be ok if you can get a good deal on it, but you will run, at best, 250x2 if its bridged.
3) Depends on the speakers. You probably CAN, but you probably dont WANT to. I'd be a better idea to pick up some nice pioneer 3 ways front and rear off of ebay for around $50 a pair if you really want good sound quality...... OEM systems are not known for their SQ
I would recomend AT LEAST 8 guage, preferably 4 guage for that amp (i know i cannot spell) a basic radio shack or rockford fosgate from best buy wiring kit for 4 guage wire will come with everything that you need, such as speaker wire, RCAs, remote turn on wire, etc.
If you have any more questions - you can reach me at AGoodbar@charter.net or on AIM as AGoodbar (I like to keep my names simple )
Whew..... My fingers Hurt.....