obviously tobi is not madara, since madara just got revived with edo tensei he must have been dead a while, but there seems to be a link between the two and their history, I came up with a theory that might explain this link and how they both seem to know the same things.
I haven't read all of the previous posts in this thread since that would take a long time, so if anyone came up with a similar theory I do appologise.
I think that tobi is a sort of copy from the real madara but a special kind, and they are two separate beings but with identical memory's at the moment tobi was created. I also belive that the difference between the actual madara and tobi can be made by the hair. I dismissed this earlyer but now with the recent chapter I have to revisit my thoughts. for the creation of my theory I have also separated the actions of tobi and the real madara based on the length the hair.
now, firstly, it all starts with the real madara fighting with hashirama senju, the infamous battle that he supposedly lost. tobi mentioned that this fight was done to gain acces to the firsts dna and his powers(chapter 510 page 12), presumably to gain acces to a proper inzanagi. I asume that madara survived barly and hid himself somewhere to recover. while doing so he must have began to experiment with the dna he gatherd. he might have done this on others first and eventualy on himself.
white zetsu is obviously a creation of that dna (as explaind in chapter 512) and I think that black zetsu (at that time a regualr shinobi loyal to madara) was the template for the first white zetsu that got copyd into 100.000 for the war. so white zetsu was probably sort of his first human experiment befor perfecting it for use on himself, thus finaly creating tobi by mixing madara's own dna with hashirama's dna. this possibly gave tobi the full memory's of madara (or the memory's were added later), explaining why he knows things in detail about madara's life. it would explain also why tobi can switch arms and eye's quickly, his body must be quite adapable because of this tech and it explains why he looks like zetsu when he is damaged. however I think the EMS was not copy'd and that's why tobi never used anything more then a regular sharingan. posibly also why he has such a large collection of sharingan, to compensate for any losses and provide the tobi body with sharingan to begin with.
tobi and madara probably also look alike since kisame first met the real madara (long hair chapter 507 page 13) when he discoverd that he was controling the fourth mizukage and later on when tobi showed him his face he recognised tobi as madara (chapter 404 page 2).
also I don't think that madara created tobi on his deathbed, they must have lived alongside eachother for some time. tobi attempted the attack on konoha with the ninetails by order of madara and the real madara was later found out by itachi (notice the long hair, chapter 400 pages 8 and 9), who probably did not know about tobi's existence at that time or just asumed that they were one and the same. that would probably also give reason to belive that tobi and madara share the same chakra. the real madara probably helpt itachi out with the massacre of the clana and must have died shortly after, he must not have been imortal, and he must have left instructions to tobi (who already created akatsuky at that time) to manipulate nagato into using his rinnegan to bring back madara when the time was right.
this last bit would explain why edo tensei madara first thought his revival was nagato's work and why tobi got frustrated that nagato used the jutsu to revive the people of konoha, mentioning that that jutsu was intended for him (chapter 453 page 17). madara knowing what edo tensei is must also prove that he lived in the times when the second hokage created this technique.
your comments are welcome, and any remarks or input is helpfull, be it positive or negative.
but no mater what the truth is, it's certainly going to be an interesting few chapters comming up