Could you also remove the "Debain" branded wallpapers and add those pictures in the wallpapers list (that appears in the settings) :

I think I can answer this one.
Our repository is synced with Debian testing's repo. Debian is currently in a frozen state until the release of Debian 9 which should happen very soon.
After that, things will be back to normal with the rolling release until the next Debian frozen state (every 5 years?)

Also, the package python-dev cannot be installed from green :

Thanks mak!