New E53 owner - couple of questions

[M57]

Hi all, end up having to pay to subscribe as it doesn't seem like the mods are actively looking at new user sign ups! However...


I have a 2004 E53 3.0D sport, and have already fixed a fair few problems with it, but need help with the following:


1. Right side (driver) adaptive Xenon light was way higher than it should be, but did actively direct light up down left and right when needed. I have checked the only headlight level sensor on the right side front axle (is it supposed to have two?) and it is fitted correctly. I have adjusted the level on the light itself, but it seems like it 'resets' itself? So I never have the correct beam.


2. I have ISTA+ (and INPA) and seen that I have faults:
a: IHKA: AUC sensor - which I believe is the sensor monitoring air pollution, which I would replace, but I also have:
b: DDE: Electric fan - short circuit. Are they both related?


3. The temp never reaches half way, is this normal, or should I replace the thermostat?


Thanks in advance!