I would add the entire amount of snails, hermits and shrimp at once. I temp acclimate the snails and crabs and in they go. Now the shrimp on the other hand will require a much longer acclimation period as they are very sensitive to salinity and ph. I usually temp match them in the bag and then add water over about an hour and a half.
ALSO, I hate to tell ya but a blue hippo shouldn't be in a 57g tank. they require a 6 foot long tank and at least 125g but preferably 180g.
The others on your list look just fine though.