#5 id say do the oil change yourself, or a garage you trust that knows about these cars. seems like the cap wasnt installed correctly.

#6. check to see if you have brake lights, also check your cruise controll if those doent work its your brake light switch. same thing happened to mine. its located behind the brake pedal. the part is about $120 from the dealership, you might be able to find it on line and just a 30minute job, much less if you know your way around a car.

#7 does sound like the CPS. you should get a check engine light though. pretty common issue with our cars, again 30 minute job.