Hashi's dead cell is deadly to whoever implant it into one's body and can create a massive forest neg diff in a second, that is very potent. Madara created a problem, because so6p doesn't want him to get rinnegan. When madara finally awaken rinnegan, so6p consider that's a big problem
If so6p gives sasuke his chakra/eye, sasuke could have two rinnegans as well, so one eye sasuke doesn't prove anything.
Indra's doesn't have sasuke's yin power because sage himself said he didn't give indra anything, and tried to change the cause by giving sasuke something, only to says sasuke is still a failed experiment like indra even after he spoodfed him yin power(he neglected indra before)
Well we never seen madara nor nagato nor so6p nor kaguya switched rinnegan back to normal eyes
Why he closed his eyes?? It's the same as part 1 itachi has to rest years after one amaterasu shot