I think you're a little off on the idea of the hyuga eye, he said it was a souvenier from a fight, which in all likeliness means he defeated an Hyuga and was able to salvage 1 eye from the remains. As for Danzoi's eye... seeing as just before zetzu appears hes speaking to madara... could it be that in the past Danzoi and Madara were in league with each other? and that the eye was a gift from Madara for Danzous coop? (unlikely I am sure but just a theory). Considering that Danzou is the head of root, its not beyond imagination that he could have retrieved it.
I believe that zetzu has appeared speaking about sasuke to cement the notion that sasuke is an international criminal and that thus make it easier for him to maintain control over him. After all we've already seen that sasuke wants to leave on his own scene, but with all the great ninja villages against him, it would be easier for madara to convince sasuke that he NEEDs the support of akatsuki.
rubbishcould naruto have gotten where he is without kyubi?? nocould sasuke have gotten where he is with out sharingan? no