Well, the man to the left of Red Dog (our view) is surely Living Bear - isn't he? The man kneeling at the right of the photo may be Red Fly, who has a kind of long face, though this is not much to go on. No idea about the other. I see the name Sky Bear rather than Bear Skin
Mr. Beauvais is likely Geminien Pierre Beauvais, a former trader and favorite of Red Cloud, who wanted him as superintendent of his agency in 1870. He was also known as James Peter Beauvais ("Jim"), but I hope others know more about him.