About the whole Full Link crashing ordeal; I narrowed the Android Auto crashes down to when your phone battery is full. I really don't know why this would even be an issue... It seems VAG desperately needs some proper software engineers.
Did a test today, starting the trip with 94% battery in the phone. Everything was fine until it hit 100%, it then crashed and kept crashing... Restarting the head unit or the phone does not resolve the issue.
This sucks especially for long trips, since the phone charges when connected...
-- EDIT --
I've done some additional research, and it seems this issue isn't limited to VAG or any particular Android phone. It seems that when a phone reaches 100% charge, it resets the USB connection to stop the charging (preventing battery damage). This reset, however, disconnects it from the head unit and leads to Android Auto crashing. The phone will continue to charge up to 100% and stop charging, causing the endless crashes we're experiencing.
So far I haven't found a fix for this...