Carolin's got a very nice and well-furnished flat having everything you might need during your stay. Since it's the place where she usually lives, you may find her stuff all around the house, but that ain't a big problem.
The apartment is situated in Moabit, not so far from the centre (you just have to take the TXL bus towards Alexanderplatz); I have to admit there's not a lot near the house though except for a supermarket and some restaurants.
Carolin's been so nice to me and my friends and she'll be willing to answer any question of yours.