What's the problem with this tablet? Why can't I just insert the USB and mash F12 until it boots? The tablet is made to run Windows 8.1 and Windows 8.1 only. Because of the stupidity that is UEFI (specifically it's "Safe boot" feature) we can't just boot from any USB stick we want.
Also, because someone thought putting a 32-bit UEFI on a 64-bit system was a good idea.
NOTE: This guide focuses on installing Ubuntu alongside Windows. If you're trying to replace Windows, then I assume you know enough about Linux to know which parts to change.