Several Curious Charging Questions

1) If you have hilltop reserve on to limit your max charge to 90%, how does cold weather change the equation? For instance San Francisco is having some cold weather, and the mileage estimate is going down from around 212 to 180. If my charging session is complete in the morning, is the battery still charged to 90%? I was wondering whether the lower number suggests that maybe I might disable Hilltop. In truly cold climates much more extreme than San Francisco, I wonder how much more the maximum range is reduced.

2) I have the feeling that my 30 amp home charger slows down the number of miles per hour of charge, but I haven't actually tested it. I was wondering if this generally happens and if so, what exactly happening? Either the rate is slowing and it is actually not using as much power, or it is using the same amount of power but I am getting fewer miles per KWH. If the latter is true, then one might have incentive to plug the nozzle earlier.