Using Tablets as Third Interface

Hello 8Forums, I'm new here (unless this is 7forums ). Pleased to meet you

I was about to post this in the tablets section however, I'm not very sure.

My only disagreement with Windows 8 is when I don't have a touch interface to navigate through some parts of the UI. I am hoping to upgrade this PC from 7 to 8 once I get an answer if it's possible to link a tablet as my third interface hardware aside from my mouse and keyboard.

I don't mind the always plugged/charged aspect of the tablet if needed as I am at the moment making a new desk and will be including a tablet mount in the design. This thought came as I had once been shown by a friend of mine (who's overseas somewhere right now) that he did it but perhaps that was done remotely through an app?

If possible

Are there any limitations to this (tablet type branded vs china made?)
Input Lag?
(Prefer not to bluetooth it to my mobo. USB connection to constantly charge it and in hopes for the best latency)
Cost?

Regards,
Shawn

Edit : Just realised there's no psu listed in the spec list. Plenty of overhead at the moment 1200W powering Xfired 7970 DCU2T