Use a line converter to get a signal for the amp http://www.trademe.co.nz/motors/car-stereos/other/auction-1189515191.htm
The jvc's will be fine for the back doors. Components are better suited up front
Edit: These are type r's btw (will require spacers) http://www.trademe.co.nz/motors/car-stereos/speakers/other/auction-1192447145.htm
In that case you will have adjustment screws on the back of your headlights to adjust the angle of the beam.
The suspension would level it to a point I guess
Ah ok. So that would explain why @JGM didn't notice the little headlight sensors when he swapped his suspension. So it would be safe to assume he has a thumb wheel?