I might not be understanding what your overall objective is, but I will answer your individual questions the best I can.
The profiles you install in Windows XP don’t do anything until a program or driver calls for them to be used. In most printing workflows you have the option of using a profile in the program itself (the Photoshop print dialog window for example), or in the driver for the printer (ie: the Sony driver dialog that shows up after you click “Print” in Photoshop). By default this driver color management is left on so that most people can get decent colored prints out of basic programs like Word or Paint. So one of the first things you learn when you want to take control of your color management is to turn off that color management (use of profiles) in the driver so that the color conversion is only taking place one time, in one place - ususally in the program.
But it is one or the other. And both driver and program access the profiles from the same location in that color folder in Windows.
I am not familiar with all the details of how the OS talks with the driver. Practically speaking we just make sure CM is off in both places when printing a profiling target, and there are several ways to confirm that. Once you have a properly printed target, you can read it and build a profile & apply it in one place in your workflow.
BTW, it’s very rare that a true CMY profile would be needed. If you are printing through a driver, even to a dye sub printer, it’s most likely that you would want to build a typical RGB profile.