Beware of keeping coral-banded shrimp with other shrimp. Otherwise, they usually coexist well with each other. Some shrimp (e.g. camel-backed) are not reef safe. I have kept cleaners, blood red, tiger pistol, and peppermints together.
Even cleaner shrimp cannot cure ANY infections. IF they take to your fish they will lower parasite numbers. However, most of these parasites are also in the gills and cannot be treated by cleaner shrimp. They may decrease stress on a fish to allow the fish enough time to develop natural immunity.
I agree that shrimp will eat practically anything. When I go on vacation, unless it is going to be for longer than 7-10 days, I don't feed my tank at all. (I am more worried about having someone add freshwater.) Many more fish die from overfeeding than from starvation.