The shrimp will be a snack for sure.....I tried a 4" purple lobster once....went into the tank the same day as the 12" snowflake (at lunch)......by the time I got home from work the lobster was in about 4 pieces. Hard lesson learned. I have large turbo snails in the tank with no problems though.....they are also co-existing with a 30" Zebra eel, 2 eels, and a trigger.....nobody bothers the snails.....
I have a large tiger cowrie and a large hermit crab in there also......no problems there either.
Not a lionfish fan so I can't say about them, but your snowflake should be OK with turbos and very large hermits.