Do you think I can put small goldfish, 3 snails, and 2-3 ghost shrimp together? I've heard about goldfish eating shrimp before, but what if I put a lot of hiding places for the shrimp? Should I add the shrimp, or is it just a waste?

The goldfish will eat the shrimp if they are able to fit them into their mouth, even if there are good hiding places.
Goldfish also love snacking on snails...
If the snails can fit into the mouths of the goldfish,
They will suck them right out of their shells.