[Perfectlap]

The first kit you should buy for your upcoming purchase is the Flat6 Innovations IMS kit. Assuming it doesn't have it already. Take care of the engine before doing cosmetics.

That 996 2002 facelift will cost you a big chunk of change. New fenders, bumper, healdights, I think hood, some stuff behind the bumper and the bodyshop labor will be steep. I'm guessing the headlights alone will set you back close to $2,500 and buying used headlights is a really unwise move. That kind of dough is not something you want to do without a warranty. You are better off buying a Boxster that already has a 2002 facelift unless you own your own bodyshop.
I would suggest going with the factory GT3 MK1 front bumper which is much more fluid than that Tech-Art design that really clashes with the underlying design of the Boxster. It really looks bolted on like something you see in the toy car aisle at Target. I think the GT2 bumper would have been better but that's fibgerglass. The RUF bumper is also nice but also expensive and that's if you can find it.

As far as Navigation systems the AVIC series from Pioneer seem to be popular with Carrera and Boxster audio types looking for a double DIN solution. I think they're nice but in six months they're obsolete and way over-priced. My Android phone has better nav/audio software just suction cupped to the windwhield like a portable GPS. and no break-ins because I take it with me.