Hi,
My experience with devices like a Tablet type PC is that I need to use a wall powered USB 2.0 hub to plug the needed stuff into...
Most of the Bluetooth stuff, touchpad, touch screen, and etc will not work when booting with Installation\Repair Media...
I plug the Installation Media Flash Drive, Mouse, Keyboard, external drive, and anything else needed into the hub...
If you physically don't have a USB mouse, cheapo ones are available for as little as $2.00...
I am not 100% sure how to show hidden files from a command prompt, but if you copy the entire eMMC drive (C:) to your external drive they will get copied... You can then set the Seagate to show hidden files to make sure they copied...