A cursory google search for Bannana Pi GPIO gives a helpful result:
Given this is my first project with this dev board, I'll have to do some reading up on GPIO. Switched USB is simple enough both circuitry-wise and software-wise that it shouldn't take too long
Similar linux SOC-based dev boards sometimes involve writing to memory locations all "F"'s or all "0"'s, or messing around with some kind of register.
I'll probably whip together some schematics, but the project is too simple for this to be worth the time.