The con guide has one thing that isn't completely correct for EF: the "stock up on sandwiches and drinks and bring them downstairs to the con area" part. Please don't do that around the hotel bars and restaurants in the lobby.
Fully agree about "bring cash"! EF has managed to empty out the ATM in front of the hotel. And credit cards aren't as common in Germany as in other parts of the world. Especially the small and cheap restaurants like the Döner Kebab vendors in the neighbourhood only accept cash.
