here is my workaroung for the brightness issue. Not exactly a clean or safest one but it works.. if someone finds a better way I would happily learn how.
1. SUID the executable /usr/bin/setpci:
2. Create a ~/.backlight directory and copy the contents of the included archive into it.
sudo chmod 4755 /usr/bin/setpci
3. Copy the contents of profile_added_lines.txt to the end of your ~/.profile (you can then delete the txt file).
In the file current_value.txt there is a hex value for the actual brightness setting which range from 00 to ff. The scripts up.sh and down.sh actually increase or decrease the currently set value and update the brightness level via the setpci command. This way can be stored any desired value of brightness and it is even held after reboot.
4. add two custom shortcuts in your keyboard setting with the following commands:
bash -c "$HOME/.backlight/up.sh"
5. Associate keyboard shortcuts with the newly created ones. Warning: the standard FN+[LEFT] and FN+[RIGHT] do not work, I use CTRL+SHIFT+[LEFT] and CTRL+SHIFT+[RIGHT] instead, but whatever..
bash -c "$HOME/.backlight/down.sh"
Hope this helps to someone.