ok...ohm(measure of resistance) loads are determined by the speaker.
we will use subwoofers for an example: one single vc(voice coil) 4ohm means you can wire the one coil to an amp @ 4ohm total load.
dual vc 4ohm means the sub has a pair of vc's that are 4ohm each and you have to wire each to be able to handle the full power rating. parallel 4ohm vc's = a 2ohm total load and series 4ohm vc's = 8ohm load.
A link to play with and learn some
http://www.the12volt.com/caraudio/woofer_configurations.asp
Once you know what the total load will be produced by the sub woofer, then you can find an amp. For the FiQ, you will want no less than 1000wrms. Assuming you get the dual 2ohm sub woofer and parallel the coils, you will have 1ohm total load. this means you will need an amp that puts out 1000wrms @ 1ohm to match rms(continuous power) of the sub woofer.
you can put a good bit more power to a Q than 1000wrms