1. the car was not locked most of the time, just sitting in the garage and getting charged when necessary
2 and 4. I did not keep close track of numbers, but typically when the range got down to 30-40 miles I would plug in the level 2 charger and after a few hours it was up to 60-80, This was consistent with my experience at other times so I assumed that the battery was indeed discharged.
3. press car, select setup, then select factory settings at the bottom of the list. There are options to change specific settings or to reset all to the factory settings, but you have to confirm this choice to avoid blunders.
5. There were substantial temperature changes during the time when this was happening, and my estimated drop of 5-10 miles per day took account of this. When the temperature dropped overnight the charge dropped more, and vice versa. On a couple of occasions the temperature went up overnight but the charge still went down.
6. I do not use my phone or the internet. Everything I have reported is based on sitting in the car and pressing the screen or reading the gauges.
My experience for the past six years is the same as yours, aside from this notable exception. I have left the car for a couple of months sitting in the garage while I was away, with no concern about discharge of either battery. On those occasions I did not record the read-outs before and after, but I have done that on numerous occasions overnight or for a few days, with zero difference in the range except when there were significant temperature changes.
2016 e-Golf SEL
2017 Golf SportWagen
2009 Jetta TDI