One thing I find about the tire pressure...no matter how often you check em' all you need is a day or night where the temp drops or rises 30-40 degrees and the tire pressure changes. As for the washes..I was out in 34 degree weather washing my car this winter, I don't think I missed a week but then again I'm crazy or so I've been told. It would have to be a pretty serious situation where I'd put it through a car wash, no telling what goes on in those things.
Best of luck with your car!

Pat