Alot of the references say that a 30 is big enough:
"It requires the minimum of a 30 gallon tank with lots of hiding places and live rock for grazing. The Flame Angelfish is prone to nip at stony and soft corals (sessile invertebrates) and clam mantles. If the Flame Angelfish is to be added to a peaceful community, it should be the last fish introduced. They adapt well to aquarium life, but should be kept in an established system and housed with dissimilar genera."
I wouldn't personally do it, but I know how it is to have your eyes set on something
I am bad about that too, but again it might be bad for your soft corals etc. Have you looked into a pair of percula clowns, maybe some clown gobies, or a sixline wrasse, or royal gramma, they are all cool fish. If you are really into this saltwater gig you will probably want to upgrade your tank soon, so I say do what you feel is right for the fish, consider the size, etc. It would be better off in a 55g or larger probably.
Macro algaes are like caulerpas, you would want Chaetomorpha algae, it's in my refugium pic.
With your lighting you need to definetly consider some zoanthids, shrooms, maybe some leathers too.
Kyle