i've been observing the Manga Almost everything concerning Madara, is linked to Orochimaru. I hope this answers/theorizes some questions you guys may be wondering.
1) Lets say Madara died in the "World between this and the next"...then How did Kabuto get his Corpse?
- My guess is Orochimaru some how had it. Preserved also:
2) Why was Orochimaru experimenting with shodai cells with children and Danzo?
- I say, For Madara. To make them "Compatable" to humans, for his use..which resulted in Kabuto's version.
3)How did madara do this jutsu:
Orochimaru speaks of it here:
4) How can Madara's Edo be so young and He's so old?
I'm guessing that Your resurrected in the state that you died, and not really your age.
So if juugo died after he gave sasuke chakra and turned 16 again, then his Edo would be 16yrs old...until it absorbs chakra to get him back to his "supposed to be" Age.
Orochimaru speaks a bit about it here: http://184.108.40.206/manga/mangas/Na...1%20-%2015.jpg
What do you think?