I use mobil 1 5w-30 from Costco.
As for parts. Your choices for retail are pretty limited. There's Pioneer that pecival mentioned, if you're further north, Hoehn Porsche. There's a shop off mira mesa, AJ USA
http://www.ajusa.com that carries some porsche parts as well. If you're a PCA member you get a discount at Pioneer.
For maintenance stuff, i recommend you buy online. I have found it to be cheaper. I buy all my maintenance stuff at Pap Parts.
http://www.pap-parts.com/
Good Luck,
Larez2