In Germany do you need a C or F adapter to charge phones, iPad, etc.
generally a C or F works in Germany.
A two pin, type C adapter, sometimes called a "europlug" adapter will work fine for USB chargers. Reason: USB chargers are double insulated (square in a square symbol on the spec plate). They don't need a ground, which the type F has but the type C doesn't have.
The type F Schuko adapter has a ground, but in the case of USB chargers, it isn't needed.
Will an F type work with USB as well, even though it's not necessary?
Yes, a type F adapter will work with a USB "charger" in Germany. In fact, that's mostly what I use (actually a type E/F, which adapts to both French and German Schuko receptacles, which are used in most continental European countries), but a type F adapter will not work in Switzerland due to the shape of the recessed socket.
Here is a good website to read about plugs and receptacles all over the world.