Jonah......Best Buy can't tell you anything....they don't really do any custom work, I know, I used to be a supervisor at store 135 in Pleasant Hill, Ca.
Your best bet is going to be to take everything you have to a custom install shop with some creds. A nice fiberglass set up would look awesome in a ride like that, but you would need to find someone who knows what there doing with it.
One thing I can tell you is your going to need wire and alot of it. I would suggest 2 gauge from your Batt to your caps, 4 gauge from your caps to your amps and run no less than 8 gauge from your monoblocks to your subs.
I would also advise getting a seperate digital crossover for your subs, your amps may come equipped with them, but trust me they never work as good as the seperate ones, never. You should get a digital voltage reader as well, unless your caps come with them on top, well even still with that equipment I'd get a seperate one as well to monitor the voltage just before it reaches the amps.
I would also suggest alot of Liquid Poly Foam, or Dynamat lining. I know alot of people think that it doesn't do anything, but your vehicles ability to hold SPL ( sound pressure level ) is soley based on the density of the materials in your car and what its made of. When your vehicle vibrates or shakes pressure is lost by the movement of the metals. Harding up the surfaces will retain a much greater pressure and in turn generate a louder truer sound.