Also, what kind of actual range should you use between charges to optimize battery life?
Optimize Battery-This isn't a cell phone. "Tesla battery degradation at less than 10% after over 160,000 miles, according to latest data"
The batteries aren't as different from cellphones or laptops as you'd think: the cars by default limit standard charging to 80% or so of the battery - you'd go over that if you're traveling out of town.
Regarding the 40% range degradation when it's cold out: I wouldn't be surprised if that number is actually higher when it's sub-zero out