Sorry for taking so long to reply, ive been on vacation this summer and havent had a chance to get to a computer. But THIS IS GENIUS. To be completely honest most of it was kind of common knowledge atlthough it would have taken a bit of reading to find absolute truth but it was very nice to see it strung together the way you did. The obito thing was a bit of a twist, personally I would think Madara's Edo would have been Orochimaru's vessel as it is immortal, has both senju and uchiha DNA, can switch between MS and Rinnegan, and would also explain why he was experimenting with kabuto in regards to madara, as they already knew how to revive him in his "prime/golden years".
One thing I would say is that Orochimaru doesnt want to be immortal, that is a common misconception. He wants to unravel the secrets of jutsu, which requiers mastering all jutsu, which takes times. And thus him needing to be immortal is merely a side effect of him wanting to master all jutsu, so i dont think him wanting to be immortal actually counts as a goal persay, could his alliance with konoha simply be a chance for him to grab madaras body?
All in all great thread shouri, I am impressed.