Most every cable company disables the USB, Firewire, and any other port built into the boxes.
good to use to power up an IR remote extender or HDMI extender/splitter for another room.
USB power is pretty limited though.
As for all box options listed by the manufacture, most are not available and it's why the cable co's have a box guide specific to their system.
They buy them in lots of 500,000 they can even have them lable them if they wished. Can charge your phone too., if its hot.