I think you trying to understand how all the system works before even touching an install disk. This ain't going to happen. You need to install linux on your spare machine and search solutions for each little problem as and when they come up.
Imagine a Mac user who has only heard of Windows coming to you and asking you how to install Windows+drivers+software+utilities+security and at the same time asking questions like how do you set up file sharing, whats the start button do, then multiply that by 10 because linux gives you so much more control, then thats the sort of position your putting us into with your questions - theres just far too much to write down in one go and certainly far too much to drag out of my poor little brain in one go
Just get it installed, keeping your other Windows machine close by with your browser and google handy, and then if your really stuck you can ask specific questions on messageboards like this one