Helmut Is a good host, and very helpful too. He was in regular contact leading up to our stay and always replied promptly if we had any questions.
The apartment has everything you need to compliment your stay and there are additional helpful guides and leaflets.
Transport links are fantastic in Berlin, indeed there is a U-bahn station just at the end of Germania strasse.
There are a couple of supermarkets nearby that should cater for your needs and also several eateries serving different quisines.
In short it's the perfect place to stay, we are definitely considering returning as we enjoyed Berlin so much.
Chris and Sarah