From a wiring perspective, you can think of a DVC sub as actually two subs. Where a SVC sub has one positive and one negative connection, the DVC sub has two of each. This allows for a lot more wiring combinations (especially when using more than one sub) allowing you to lower the resistance, and thereby pulling more power from your amps.

As far as how much power to drive them with, I suggest running them at 75 - 90% of thier max RMS. I'm running two Orion P2D4 12" subs (500 RMS/1000 Peak) at around 400 - 450 RMS (my HCCA 250 is rated at 800 Watts Mono, but probably maxes out at around 1000 - I usually keep the gain turned down a bit though).

For good info about car audio/video installs, let me suggest http://www.soundomain.com.