The apartment it's exactly how it's show. Karsten is a great host, he dedicated the time to explain us everything about the apartment, the neighborhood, the public transport and about Berlin.
1-the apartment is one block from the subway, but to go to some turistic spots you have to change trains. It was not a problem for us, because he explain us how to use public transport and he also gave us a map.
2-There is a market two blocks away and a Deli one block and a half that it's open till midnight.
3- 84 vietnamese vegan kitchen, it's a restaurant near the apartment. The portions are huge, it's cheap and the weitress speaks english well.