I hope you didn't get a green brittle star with that package deal. I have one and they are NASTY.
You should have a cleaner shrimp or shrimps,the kind and amount of snails is based on if you have substrate or not and how big the tank is,and if you will have light or unanchored corals in the tank. I dont trust hermits, they kill and eat snails.I had a hermit eat a flame scallop on me also.
Pretty much its not best to go with a package deal but maybe it will work out for you...
Cheers!