XG1 box question

I recently got an XG1 Xfinity box. Hooked it up and all works good. I see on the back of it how it has an "HDMI in" port. While its covered and assume not be used, is it possible to still use this "in" port?. Was hoping for a video game system/console or even a fire stick or Roku (that would then operate MUCH faster for apps than the X1's).

I also see USB and eSata ports. Can these be used for anything as well (like additional on-board storage).Just curious