Well, Madara never said that he cooperated with Tobi, rather he only said "It's his doing" and not "their doing" (560 page 3). Don't you find it strange ? Zetsu is an important factor (the black one even more ?) that seemingly helped Tobi from the beginning and even gives Tobi spare parts. What's more, Zetsu could have taken the form of Madara with Madara's chakra (they probably have it somewhere) and thus could have been considered a "fake Madara" (561 page 13)... it's possible that Madara doesn't even know about Tobi.
People are saying that Tobi is Izuna because he knows too much, but Madara suggested that it's (hard but) possible to put the puzzle together by reading the Uchiha Stone Monument (560 page 16). What's more, Itachi mentions that he saw Tobi going to the Uchiha hideout to read the Monument (590 page 17), that's a strange and unnecessary risky action for someone that supposedly already knows everything...
The information about the jinchuriki seal weakening at the time of giving life, would be impossible for Madara to obtain, unless he somehow got his hands on another bijuu, sealed it in a women, impregnated her and then watched if there is any weakness in it. The only one who could potentially obtain this info, is Zetsu (unless someone betrayed, but that is unlikely).
I'm actually wondering about how So6p's Mystic Face looked like. If from Kurama you gain the Heart Opener aka Talk to the Kitty (it's special property is that it makes anyone that sees it, want talk about themselves, thus allowing later on for Talk-no-jutsu to work ), then what kind of marks had So6p obtained after becoming the Jyubi's jinchuriki ?