Questions about rooting a tablet device for making kiosks
For a solution like a kiosk you would use dev hardware where you have full access to the hardware (JTAG for example) and then you would push your own Android build with root access enabled and then push the ROM to the dev board.

That said, for a kiosk type deployment you would NOT want root access available. Therefore when you push your ROM root would not be enabled. 

I think your confusing root access and an unlocked bootloader. 

By a dev board and learn how to build your own ROMs. :)