There is a small kiosk at the far end of the U-Bahn station Thielplatz where you can buy newspapers, cigarettes, etc. You will also find some snacks. At the close end of the U-Bahn station there is a snack shop offering salads, sandwiches, yogurt, etc.
For breakfast you can visit the restaurant Aux Delices Normands, Ihnestrasse 29, 14195 Berlin (Mon–Fri: 06.30 am - 6.00 pm).
Another kiosk can be found close on the FU Campus (we are passing by every day, after lunch).
There are a few cafeterias in various buildings of the FU, ground floor of the cafeteria and in the basement of the Faculty of Law, which is across the street from building D.
In Steglitz you can find a high density of shopping centers located at Schloßstrasse, including 3 major Shopping Malls:
In Zehlendorf Mitte there are many shopping opportunities around Teltower Damm: Zehlendorf.com