they could not bring madara back before because tobi did not have all the tailed beast. the time differences are there .... i dont know at what time was that scene when they went back at kisame flashback im pretty sure it was tobi.
I dont think tobi actually considered himself to be marada it just gave him credibility and a name that people fear, so thier mission go go along a bit easier , he told kisame he was madara so there could be that fear in him and to show his power also not to disobey, didnt you see how relieved he was once tobi sowed kisame his face. like"oh now that i know its you i feel better about the plan"
If that's the case then why grow your hair out then cut it? There's absolutely no reason for that unless Obito really thought he was the new Madara Uchiha.
Why would they need the tailed beasts to bring back one man? Nagato was a lab rat and nothing more. He had one purpose. Unlock the rinnegan powers, revive Madara then die. PERIOD. But Tobito didn't tell Nagato about the real reason he needed the Rinne Tensei I bet. I have a strong feeling it was intended for Rin.
Why would he ask kabuto how to stop Edo Tensei? I don't think he would've cared how it worked if Madaras corpse wasn't in that Coffin.
He did not want him around at all. He went by Madara almost till the very end. Than when he was figured out he knew the jig was up. And the real madara was around, so why keep the act going?