[SD987]

Question 1:
Motor problems are difficult to pinpoint with anecdotal data. Basically, there's in-warranty and out-of-warranty. If your engine grenades and you're in the former, you're fine...else, not so much.

Question 2:
If you're concerned with performance the two 987 options that would most impact performance, except for ceramic brakes, would be PASM (adjustable suspension) and Sports Chrono (more responsive accelerator, reduced stability management intervention).

Question 3:
In terms of knowledgable contributors on the 987, I'd rank the Boxster forums as follows:

986forum
Rennteam
PPBB
Rennlist
Boxa.net

Question 4:
I've owned a 2005 base and a 2006 S, neither was more reliable (both excellent) over 40K combined miles of ownership.

Question 5:
4yrs/50K. Your options as a resident of California for extended warranties may be limited. Some dealers offer extended warranties at point of purchase OR you may be eligible if you purchased the car second hand at a Porsche dealer. Tracking the car shouldn't void the warranty, but the 987 black-box reflects the improved sophistication across the industry and transmission abuse is recorded and may potentially impact your warranty.

Question 6:
Every 20K, minor/major/minor, like most cars these days. Tires can be an expensive regular upkeep item, but coming from an NSX you'll know this already. Some people feel that they know more about maintaining their Boxster than Porsche and Mobile and thus will change their oil more frequently to achieve self-satisfaction, peace of mind, and spend money unnecessarily.