Here is the fusing:
http://carpc.kyferez.com/phpbb2/viewtopic.php?t=15. Do as much or as little as you think you need.
On step 4, wire the +12 directly to the battery, to a power wire running to your amplifiers, or any other always on +12v. Wire the Black wire to the car body or any other good and convenient ground. The most that will be pulled is .2Amps when powering all relays, all leds on. (~.1A is typical max current draw).
Fusing of the yellow wire is discussed in the link I provided too.
KyferEz