Some questions about types of fish in my freshwater tank?

I think you need to do a LOT more research. Almost everything you've done so far is wrong. First, a new tank needs to be cycled before you add fish. Second, puffers and do not belong in aa community tank. Tiger barbs need to be kept in groups of at least 6, but you can do that in your tank. Clown loaches get to be a foot long, there's no such thing as small to medium sized ones. Your tank isn't big enough for them. Feed fish flakes and if possible live or frozen foods like bloodworms. Feed them twice a day, no more than they can eat in about a minute. Puffer fish need live snails. You'll probably need algae wafers for the plecos because a new tank won't have algae. Fishkeeping is a great hobby, but there's a lot you need to know. Here's a website that has lots of good info, poke around there for a few hours. Good luck.