Don't know if there is a better place for it, But have you all seen the National Costumes for the Miss Universe Pagent? There could be some wonderful inspiration for some outfits for Dawn from it. For someone talented enough!
Aha! Here it is. Now, what happened here? I can't guess why the retina is looking like a flash glow in the first one. But looking at the pair it seems the reflection is raytraced now. True? Also the eye on the right side of the first test render looks like the iris is sliced. Not so realistic. The others look real good. And emerald green! My favorite eye color. None of my iris images are this color of green.
Now, to the question of materials. The complete material would be best. Diddling with the channels one by one is time consuming and wears people out when they're trying to be creative. See, do the geek part so others don't need to. But as for style, I don't know what to say. Probably two styles, based on what you perceive as fashionable, one that is more elegant for less computing power, and one that is more glamorous.