Yes, look in XBMC and check the XCLD to on. It will display your XBMC info on the screen.
No, You do not have to use screws to hold the XLCD in place. I didnt and it works just fine. I put a little backing behind it because I didnt want any screws showing.
Yes, put some electrical tape all over the back of the XLCD screen to protect it from shorting.