I reused stock wiring with no issues at all. I also used the big rubber grommet behind the drivers side of the battery. I ran 3 pairs of RCA's no problem.
I too have a thread of some pics of my install.
http://986forum.com/forums/general-discussions/50741-changed-factory-stereo-speakers-added-subwoofer.html
I changed the dash and door speakers, put in 2 amps in the frunk and a sub in the passenger's foot well. It was one of the first mod's I wanted to do to the car. My stock stereo was crap. The dash speakers were falling apart. Acutally the sound of the factory door midbass/bass wasn't that bad but since I added a sub I swapped them out for 6.5" coaxials.
Planning to do the ipad mini/tablet install too.
PM me if you have any questions.