A scratched disc would usually cause setup to report not being able to copy certain files during the install process. Sounds unlikely it would just arbitrarily leave out files without warning the user.
Anyway,
>>1, what do you mean none of the drivers were installed? Do you mean all the devices in device manager showed up as not working/driver missing, or just some of them? Or that when you try to add new devices the selectable list of pre-installed drivers is not there? It's very common that after you finish installing Windows you have to install appropriate drivers for a number of devices, often including sound, video, chipset, USB, network drivers and more. You usually have to install them from the driver CD that may have come with your computer, or download them from the manufacturer's website (better, because you're getting the latest version). Windows isn't going to have drivers for devices that were made after it was released.