Just a thought while looking at your stocking, if that's all you have in your 55 gallon, the serpae, head and tail lights, harlquins and glowlights need to be in shoals. They won't be as happy with only two of each. Opinion differs on the number, but maybe add a couple more of each at least?
As for the shrimp and snails, I have had apple snails and ghost shrimp with no problem, unless the shrimp is aggressive (are any shrimp aggressive????) then I don't think you would have a problem with any snail/shrimp combination.