Let's answer some. Although CDs and DVDs are the same size, they are different technologies. Look on the front of your CD-ROM drive. If you see the DVD logo, then you really have a DVD drive, which also can play CD-ROMs and music CDs. If you just see the CD logo, then you can play CDs and CD-ROMs but not DVDs.
Installation is a breeze.
Just plug the USB version into your PC, install a CD and reboot. Connect your computer to your phone line. Do the same thing with the other PC and you are connected. It works very well for Internet connection sharing, as well. Hook one computer to the Internet and share that connection with the other PCs.