If your lights go dim at idle or when the sub hits hard you need a cap, dont get a cheap thing either get something nice that will prevent it from happening.
As for your amp, it is not cooling, is yours fan cooled, if not then when you get your new system get one that is.
Also stuff could be blocking its way, where is your amp under the front seat, or in the trunk?
With wiring Best Buy said they have to remove the panels along the bottom on the door, but attached to the car not door I mean, the ones held on by phillips hedas screws and wire it underneath it most likely.
