The clowns would be a great start. Not really aggresive and real great fish. The Dwarf angel is a little touchy subject. Most dwarf angels will be at least 4' when adult, or more. The one i had
This pigmy will go up to 3'. And they usually come very small, unlike others Dwarfs that are usually bigger when u see them at the lfs
. Plus most drawf angels are aggressive, which means it has to be your LAST fish to be put in.
Yes you should get at least 1 powerhead in there, maybe even 2 smaller ones.