The prehistory museum in Charlottenburg is quite decent, and there's the palace and gardens to explore to make it a worthwhile trip in any case. Lots of WW2 related archaeology, obviously, but you need to do your homework as next to none of it is signposted.
Don't forget the interesting places outside the city, Sanssouci, the Wannsee mansion etc.
As for food and drinks, beer and schnitzel/bratwurst is everywhere, and what else do you really need?