pslsnakes, thats truely a good picture of groud looping the rca outputs. as for power, using the factory harness is fine, howver, if you plan to upgrade your system, i suggest you run dedicated power from the battery and still use the harness. THat means, connect all wires from aftermarket deck to the factory plug in harness besides GROUND and CONSTANT 12v. that way your deck will run at its best if it has dedicated powers ( will draw as much current as it needs)
for my system, the only wire i used from my factory harness was the ignition. power, ground, speaker, antenna are all on its own since i got amps running fronts/rears and subs.