You will be getting close to your 30,000 mile maintenance point, the main service of which (oil/filter change) you are already looking into doing. Most or all of the other items you can do yourself if you have the time, some tools and the inclination. You can do a Search and find out about the 30k maintenance. Here's a couple places to start:
http://mysite.verizon.net/resqir1s/PorscheMaintenance.pdf
http://986forum.com/forums/performance-technical-chat/20785-30k-mile-service.html