There are no preouts on the factory deck. They have to wire amps to it with actual speaker wire if they hook one up. That's how mine is now, so when I get my deck I'm going to need to rerun RCA cables.
As far as a switch for the amp... you could really put it anywhere. If you have the action package (meaning no fogs) there is a dead switch next to your window lock button. Otherwise, you could put the switch in your center console or in your ashtray (many people have done the ashtray one).