I hope that Madara/Tobi is not the Second. That would make no sense. The second doesn't even look like he is an Uchiha. Not to mention the 4th would had to have known the Second at some point and should have been able to recognize his fight style,

And I don't think that it is out of the question that they bring the Fourth back with Edo Tensei. I really doubt that Oro would have gone through the trouble of getting him ready without knowing whether or not he could have used him against the Third.

The body that Madara saw was probably just his brothers.