1. if i remember right, centrafuse has a portion of their site that lists the minimum, and recommended hardware specs.
2. you can connect this to a acc wire--usually one in the fusebox, or from the radio harness. the other option is to connect it to the delayed amp power terminal on a dc-dc power supply-- this will delay the amp from starting up for a couple of seconds to try to keep the 'pop' out of the speakers-- if you have that problem.
3. i would not recommend it for anything more then temporary use. most cig. lighter ports are rated for about 10amps. usually enough for a load like this, but you are relying on factory wiring that might not be up to the job--they technically put it there to allow you to light cigarettes in your car--nothing else.. i know they never expected you to power a laptop from it...
by running your own power wire, you can make sure that the wire is properly sized for the load, and you can also make sure that it is grounded properly. (something that is a common weak link with factory plugs)
if you have a poor ground, it can lead to noise in the audio system(called a ground loop)-- just search the car audio section here-- there are plenty of threads about it