=> CH=380 is not really a problem; just run your TA lower. (http://pool9.net/alk-step/

=> With a high CYA, consider establishing a borate level > 60 ppm. The primary downside of a high CYA is that IF you get algae, it can take extreme levels of chlorine to eradicate it. Adding borates doesn't kill algae, but it does make your pool less susceptible. http://pool9.net/borates/

=> As mentioned, it IS typical to lose CYA over the winter. But you probably want to avoid this. Bacterial decomposition is the reason for this loss, and it can have hard to predict effects. Most often, the CYA is converted to nitrogen gas (no problem!) or nitrates (minor problem). But in a significant percentage of cases, the conversion is to ammonia, which is a big problem, and tends to ruin your spring start up.

=> In Tucson, I'm guessing you plan to run the pool all winter, and leave it uncovered. I'd highly recommend keeping 4 gallons of bleach on hand (stored in a cool place), and dumping all 4 gallons into your pool at the FIRST sign of algae or biofilm.

Good luck!