a) It is an ocellaris. Same species as the typical orange "Nemo" fish, just a different color variation. In the wild they're only found off the coast of Darwin, Australia.
b) I'm not sure at what age a clownfish is actually considered an adult, since sexual maturity in clownfish depends a lot on external environmental/social factors...maybe one of the breeders or the other more experienced people here can clear that up for both of us.
c) Many B&W ocellaris start out with orange faces that darken as they reach maturity. Some of them retain a little orange tint to their faces, or an orange "nose". My last pair both had completely black faces. I've seen separate listings for black ocellaris with black faces and black ocellaris with orange faces on some dealers' websites, so to me this indicates that at least some of them may retain the orange coloration to some degree.
HTH