First part Ray and Frank pretty much covered.
The last "Would that not increase the amps thru the entire system?" depends on the equipment added, not the alternator.
You just want an alternator that can comfortably meet the maximum total needs. If it can do it at idle speed, thats the best.
The flip side is if the equipmet is going to be running on battery (say big stereo for tailgate parties). Then IMO some sort of charging regulation is needed or the battery will get hurt even if the wires survive. That's what that guy with the camper-van has to figure out (in the amp to voltmeter thread). Deep cycles will probably handle it better, but this is the sort of scenario that needs to be figured out with someone who knows that stuff.
