Regarding the brightness bug: I found a nice workaround. The only Problem with this work around is, that "automatic brightness" doesn't seem to work anymore. I prefer the manual settings anyway.
The workaround basically removes the brightness slider in the settings and adds the basic 4 brightness settings just like phones as the Lumia 730 / 930 have them: Low, Middle, High, Automatic
How to?
1. download the latest InteropToolsApp (arm) and the dependencies (
https://mega.nz/#F!iZMhSSzI!sGQy4V12ubfvT8Abm2Uo1g)
2. install the dependencies one by one via the device portal, after that install the InteropToolsApp itself
4. Open it, go to tweaks and enable the brightness slider setting
5. restart the device
6. now open the App and disable the brightness slider setting
7. Restart - Done
Now you got the same brightness settings as the Lumia 930 / 730 and no way to get the brightness down to 0% anymore.
Edit: For some reason it doesn't seem to work all the time. After the upgrade to .82 it doesn't seem to work. It mostly works on fresh systems - after a hard reset.