How many shrimp could be added to a 5.5 gallon and what species?

There will be fish, maybe just like 3 guppies or a few more elders. Nothing crazy, just maybe 4-5 shrimp? Good idea? Also can freshwater clams go in here (replace shrimp), if so how many. Lastly, how many apple/mystery snails? Please give specific details (species, amount, compatability) BTW all male fish so no fry.