Xbox One USB Keyboard Support

This is incorrect. The XBOX One does support USB keyboards and wireless USB keyboards. I use the Microsoft Media keyboard...

ESC also functions as a back button. Also to help with yelling at kinect, I would try turning up your volume to high and slowly bringing it down to the maximum that kinect can still recognize your voice (use the "kinect can't hear me" option in settings)
.. since I've done this & had it calibrate it seems to hear me better.. I can say for example "xbox, show menu" in a lower-than-conversational voice & it hears me. Might help with your thin walls , although the calibration might upset the neighbours. lol.

arrow keys for moving about the options and the enter button to select. HOWEVER, I have yet to figure out how to go back with the keyboard. My apartment walls are thin, so yelling at my Kinect is out of the question. Hand gestures are still lacking and flawed
in my low light conditions. Using the controller wastes that battery and becomes a hassle to use more than one controller.

Tl;dr i would personally love a hot key list for the keyboard, a back button, maybe customizable keys. Makes for easier browsing of Netflix, YouTube, and tv. Maybe personal media... one day?

what all can the keyboard be used for?

Does this work with the mouse aswell and on what games