Madara was not stupid. He was intelligent being a Uchiha, just like Itachi & Sasuke; (gifted)
Madara had knew many things, since he lived longer than anyone.
In order to succeed, he must have learned many jutsu, whatever.
Don't forget that even he knew of the bijuu and SO6P, not forgetting the 1st Hokage. It was one of experiment by Orochimaru, that's how Orochimaru say Yamato was the only one that had 1st Hokage DNA, to succeed.
Orochimaru was not stupid, that could the reason why he left the Akatsuki, knowing Madara's plan.
Those Zetsu were 1st Hokage DNA.
In order for his plan to work, he need Nagato to revive him, as a normal life, just like when Pain destroy Konoha and later revived the dead back to normal life.
It was when one of Kabuto's dummy told Madara about what was going on.
Not many knew how to break the Edo Tensei, even not Itachi.
Read the manga. Part of info was from the manga.................................