1. Is the usb port on the slim just for interfacing with a computer or can i use a usb midi keyboard to control all functions - namely pitch

Basically is the slim's usb for cc 's or just sys ex?
2. Can that USB port power a "usb powered" midi keyboard (ala the korg microkeys).?
I'd like to probably get the microkeys controller for my slim but as long as i can use it to play the slim via the usb slot and have the slot power the controller as well ...
Possible?