The bettas are in what's called breeders boxes, they are used to separate live bearers like guppies and platies when the give birth to their babies. I find that bettas enjoy other males to display at, I used to keep them separately but they would get depressed and just lay there, now they get exercise trying to out display each other. I found Cory cats to be easy to keep, mine lived more than ten years, keep them in groups as they like company, and don't touch them as they have a spine in their dorsal fin, they also dash to the top of the tank to take in air occasionally. I haven't kept shrimp, they would probably do well with a Bettas as cleanup as well, and I had a plague of snails long ago and bought some loaches to get rid of them. I'm sure you are talking about Apple snails or something like those. If you are just starting up a new tank and do not have a tank that is established than make sure you buy one of the commercially available bacteria cultures to fire up the tank. Fish keeping requires tending to bacterial colonies that you can't even see, have the correct organisms in your tank and keeping fish is easy, just doing water changes every week or two. If you don't get the tank started right it will be a nightmare. So glad to hear your planning ahead. I currently have 6 tanks, two tropical, the rest goldfish, my first love, I have my big ones in a 125 gallon. I will be happy to answer any tank questions, been keeping then for 12 years, took a bit to get it right.