I am in the same boat as you. Have been a PC Tech for years now and am just getting around to learning Linux. It is SOOOOO different!
I have been trying out various Linux distos for 5 days now and I assuse you it does get easier as time goes on.
First off, I have not tried the distro you are using. But from what I have tried I am really liking Fedora 3, Xandos and Kubuntu. I would also like to know the answers to your questions. In Win programs by default go under C:/Program Files/etc no idea where they live in Linux. Good question(s) and I look forward o the answers from one of these gurus.
My advice to you so far from my experience is forget everything you learned in Windows, lol. Look at Linux as a completely different beast and do all the reading in various forums that you run across, it started to make sence to me roughly three days in = }
Another thing you will want to make sure you get is Wine from here
it allows you to install and run many common Windows apps.