To get the brightness controls (Fn + Home and Fn + End) working you need to set the EnableBrightnessControl option in you Xorg configuration.
Create the file /usr/share/X11/xorg.conf.d/10-nvidia-brightness.conf with the following content:
Section "Device"
Identifier "Device0"
Driver "nvidia"
VendorName "NVIDIA Corporation"
Option "RegistryDwords" "EnableBrightnessControl=1"
EndSection