I was getting responses from Uwe really quickly, he was waiting for us at the apartment when we arrived and greeted us warmly!
The apartment is around 20 min by train from the center, which is very close I believe. Charlottenburg palace is very close to the apartment.
The place is very calm, there is a green garden if you look out of the window. Very tasty bakery Zeit fur brot is just 300 meters away, we will miss it :)
I recommend this apartment to everybody :)