Most q6600's will do 400fsb, anything over that is a bonus.
All midrange onwards mother boards should max out a q6600, and you only need 800mhz ram for a 1:1 ratio to get you there.
For a quad the q6600 is a good clocker, but its no record breaker on the fsb front, so this 'max out' doesnt really apply.
With PROPER cooling most q6600's will do 3.4-3.6 ghz (380-400 x9) anything extra is a bonus and lots of heat.
From the questions you are asking I can tell you havnt overclocked really before so the best thing is to get some reasonable parts, read the guides and then come back and ask specific questions you may have when you have it running.