Well, if you only have one angelfish, and you start him small, you can probably get away with a 10-gallon, but if you try to add any more angels they will definitely pick each other to death, unless you just luck out big time and get two docile ones. Don't count on that.
Maybe one angel and some peaceful community fish... but remember, one gallon per inch of fish, and the angelfish will grow both longer AND taller, so he'll need most of the room to himself.
Most of the freshwater angels in a store are going to be Pterophyllum scalare. You can try to find a true wild-type, Pterophyllum altum, but most you find labeled "wild type" are going to be hybrids or look-alikes, and not true wild ones.
In short, they're pretty much all the same species, unless you find a really good aquarium store, so it's up to you what color you'd like.