Like you said, wait on the hippo until the tank has been established for awhile. They are very prone to disease and stress.
As far as inverts, snails, snails, and more snails. Nassarius snails are good, turbos are good. Get a few hermits, don't mix the scarlet and blue leg...they will fight. Peppermint shrimp are cool, cleaner shrimp, coral banded shrimp...but they can get agressive. Emerald crabs are pretty sweet too.
As far as the fish go, clowns are very hardy. I would go with a bicolor blenny or midas blenny. They are awesome. Have fun setting it up. Keep us posted with pics...we love to see eye candy!