Cabin filter is in the back of the engine compartment, right side, near where the tip of the right windshield wiper sits.

Don't have the wind deflector, and it's never really been a problem.

One of the lights you mention is the actual on/off light; the other is the actual sensor.

There's a fairly common wiring problem (so my dealer told me) with the lights on the vanity visors where the plastic hinge cracks and the wiring gets pinched and broken (preventing the light from coming on). I briefly looked into gluing and rewiring it one time, but it didn't seem to be worth the trouble.

Congrats on the car. It's a LOT of fun to drive. Some negative comments about C70's in brickboard, but the 01's seem to evade all the criticism with the microswitches in the top, etc. Biggest headaches have been tire life (abt 30K per set) and having to grease the steering stops on a regular basis (~2500 miles). The link I used to have for how to grease them is dead, but it's really easy to do and cures a noise that sounds like it would be expensive to fix.