I had wallpapered over a cement interior basement wall years ago. Recently, When I removed the wallpaper and the liner beneath it, the shotcrete came off with the paper. Is there any way I can repair these spots? Can the shotcrete process cover a garage floor that is heavily pitted, has a few cracks, and has some dirt and road salt marks? Will it hold up to road salt and prevent further deterioration?

You mention that you had originally wallpapered over a cement interior basement wall. It is not clear that the cement interior wall was placed using the shotcrete process. If it was installed with the shotcrete process, then the application was flawed due to improper surface preparation or application. There are many concrete repair products on the market which could be used to repair the surface. Many of these are troweled on by hand or sprayed. Check with a local building supply company or on the Internet.
With respect to the garage floor, we would not recommend the shotcrete process for a thin overlay on a horizontal surface. Again, there are many products on the market that are designed for resurfacing floor slabs. Check with a local building supply company or on the Internet for potential products.