+1 on the winter wheels. And I'm not too sure about the coolant because it's difficult to tell what was put into the car. I would guess it's 50/50 if it's as-built from the factory, possibly different if you ever had a shop in California change it. Wouldn't be a bad idea to change it, $190 seems reasonable for a shop, but still steep. DIY..?
Also - for sure, purge your windshield washer fluid and fill with the good stuff. I can almost guarantee what you have in there will freeze and possibly damage the seals, windshield washer tank or solenoid. Don't ask me how I know...
E92 convert. BMW Fanatic.