1. not sure, i'd say so.
2. yes, just bang the standard one back in and drive away. depending on mods of coures, bigger injectors or turbo and you wouldnt do it. The powerfc holds the tune for along time.
3. rev limiter is a fuel cut in the L-jetro version (the common one everyones got)
4. www.nengun.com - excellent price and service in my experience of late. ive spent many dollars with him.
5. not really, i dont have one. detonation registers on your check engine light when the pfc reads a knock of 60+. i dont think you'd need huge mechanical knowledge to understand it tho, it is very useful for realtime monitoring.
6. this is true and is current. apexi only sell packages and at a pretty cheap price too. check out nengun.
-rb25