PC means PC and the disabling only applies to Windows Vista or higher that use UAC.

Not sure how well the kitchen will run on a non-windows platform, never tried it myself. Could work from a virtual environment, or possibly WINE, but I would not flash via USB that way..I have had bad experiences trying to do that via Virutualbox on Ubuntu.

As to some of the questions:

XIP/SYS: I am still learning here but I believe the XIP is the kernel and startup files on your phone, SYS is the windows directory of the phone. The number associated with these is your ROM version. I have had good luck with 28011 so far, but others are out there that may be better.

Titanium: Microsoft default Today Shell for WM 6.5 Lower memory and gets the job done but lacks some of the function of Manilla.

Manilla/Sence: HTC default shell. 2.5 is the latest version out there. I prefer 2.1 on Verizon phones just because of the memory footprint.