Any angel, even the dwarf one's, will be territorial and can nip corals. So it's best to avoid them. The same applies to the puffers. They are not a good fit even though they can technically be put in a 30 gallon tank.
The Helfrichi filefish is a good choice. As is a Tanaka's Mystery Wrasse. Were it me with the fish you have planned already I would suggest dropping the sand sifter and the puffer since the sand sifter isn't going to get a lot of food from your sand bed and the puffer will be both aggressive and will likely eat any corals you put in. I would instead suggest:
Helfrichi
*CAPTIVE BRED* Black & white Ocellaris
*CAPTIVE BRED* Ocellaris
Tanaka's Mystery Wrasse
This way you will have some mid water column hoverers in the Helfrichi and Ocellaris and a fast mover in the Tanaka. And they have a diverse color spectrum. They are also all pretty hardy fish that are not aggressive to each other and to corals. Plus the wrasse will take care of things like certain pest inverts on the rocks.
The thing about the clown's is you need to get them as either juvenile or one that is clearly female and the other male. You can specify from the breeder or Internet site like Live Aquaria and they should be able to handle it. If you are buying locally get the black first and let it get established. Once it is go back for the orange. Look for one that is smaller than the others in the tank and kind of stands on its nose and kind of wiggles. This will mean its either a juvenile or its a male and its showing submission to another fish. Otherwise they can go after each other.
Something else that would be great to add to your tank would be a Tuxedo urchin. They are great for algae control and add some nice deep blue color. But they can be bulldozers so you need to make sure the rock work is stable and corals are as well. The do the work of 2-3 turbo snails (who are also bulldozers).
Another nice to have would be a Stag Horn hermit crab if you can find them and your lighting will support it. They have a coral shell that grows with them so they need good lighting. Also a 2-3 pom pom crabs as part of your cleanup crew are fun. They have anemone's on their pincers, are fish and reef safe, and do the same work as hermits which can be a real pain in the rear.
