Congratulations on your new car. I know it is fun to experiment with your new car. I did the same thing when I got mine. I really don't think that playing with "coasting" with or without gears or eco really makes a difference.
I like just leaving it in eco mode, and just driving it without big accelerations and letting the car regen slowly when I see a red light in the distance. Anything more than that is really more mental work than I will allow myself for any car. Changing the efficiency by any small percent will save me..... What..... $25-50 cents?
PS - Regarding the heater, you should not suffer without a heater. I put it at 68 degrees, in recirculate mode, and with the fan at 1. While the car is never HOT, it keeps me comfortable, and I do not use a lot of the battery...