cooling fans question.

If you have your sub enclosure laying across the "amp rack" or where ever the amps are, and you say they will not have a source of fresh air - then fans aren't going to help you much - a better system design would however.  If the amps are in their own sealed off area, then the fans are going to do nothing more than recirculate already warm air...one way or another, they need to be able to breathe, or you will have problems if the amps overheat.  Look into venting the area into the interior of the car more, or outside through a hole covered with a membrane of goretex or something like that...

Also - as far as wiring them, do not tie any fan into the remote wire - you will likely overload your head unit's turn-on transistor and fry it.  Any time you are running more than a couple amps or processors, etc on a remote line, or need to control a fan, neon, etc - do the following with a simple Bosch relay:

30 - To constant 12 volts +, such as from your amp's main power line back from the battery.  Put a 5 amp fuse on it for added protection.

87 - To the turn-on terminal of all amps, processors, and the positive power lead of neon, fans, etc.

85 - Ground

86 - To the head unit's turn-on wire.

87a - No connection

This way, when you turn your deck on, it will trip the relay, and provide up to a 5 amp (or whatever the fuse rating is) signal to the turn-ons of everything, and pose a very minimal draw on the head unit's internal circuit.  Take the negative leads of the fans, neon, what not straight to ground and you are in business.