The power top cables are very easy to replace. There are a few online guides and Wayne at Pelican Parts has a great book that shows how to do many DIY projects.
As for tires, mine came with the OEM Pilot Sports and now I have Conti Extreme Contact DW. Both are quiet and handle great.
Good luck with the purchase, be sure to get a PPI from a Porsche mechanic, and welcome to the forum.
