FDH is more than your room. The kitchen is commonly organized by the inhabitants of the corridor. In the building next to the office you find several common rooms: a library, meeting rooms, a big hall, a chapel. There is also a kitchen and a room for ping-pong/table tennis, including a football table. Downstairs you find a bar/party-room and rooms to practice your musical instrument. On the grounds of FDH you find a beach volleyball court and a barbecue area.
Where do you get the keys and how can you use the rooms?
Just look it up in the semester program or ask the advisor (Wohnheimreferent). At the pinboards you also find advertisement/poster for events in FDH.