Hi! Nice to host you!
About the apartment I live with 3 german roommates who are working in Berlin, so they are not in the apartment during the days, however they are super nice and relax and could give you any recommendations.
The apartment is 2 min walk from the subway and 2 stations to alexanderplatz also the s bahn is 6 min walk.
The location is great and the apartment as well, you have one big bathroom with bathtub and separate shower, 2toilets. The kitchen has everything you need.