Every time I take the car out, I put on the fog lights. I think the car looks better with them on than not and I'm sure that uses up more energy than the seat heat does. It wouldn't be any more than if you "raced off" from a traffic light instead of pulling away normally. I'm sure that the seat heat and fuel economy isn't an issue with these cars.
We have hard water at our house too. I wash my car at home and make sure not to do it if the sun is hot and I dry it off right away and it's fine. I DO keep it in the garage when I'm not out and that saves the paint the most. The car is so small (I'm used to washing a semi-motorhome with stacking race car trailer) that it's not a big deal to wax it now and then with liquid wax. That will save your paint too. The Chrysler salesman said to wash the car with soap and water and nothing harsh because it doesn't need it. He said the clear coat is so good, that if you wash it often, you don't even need to wax it. I do anyway.
Have fun with your Crossfire, don't sweat the small stuff!