First thing I'd recommend is growing a thick skin cos most people here aren't exactly nice and friendly; they're pretty rough, grumpy people. (I'm an exception of course.
) And be warned: Germans have a terrible accent when speaking English.
In certain areas it might be useful to know a little bit of Turkish.
For typical Berlin food I'd recommend the famous
Curry 36 or
Konnopke's.
http://www.inyourpocket.com/germany/berlin/en/category?cid=55756&chid=204
My favourite pub:
http://www.old-emerald-isle.de/
For any further advice, just drop me a line.