Minato is indeed Whitebeard. But to say Whitebeard is Minato just feels wrong. Minato is awesome but Whitebeard is in a division higher IMO.
And to Cal's question "Did Madara lose?", the answer is yes he did. Madara's goal was to take control of Kyuubi and destroy Konoha. Minato beat Madara and forced him to retreat and he removed his control. That is a loss. His goal was not to kill Kushina and Minato. Infact he didn't even manage to kill Minato. He chose that himself. it seems that Kushina would have died just from the extraction even if she was strong enough to survive it. Like she was slowly bleeding out or something and nothing could stop it. But Minato had an out to get rid of the Kyuubi and survive himself. But he chose to sacrifice himself to insure that Konoha would keep the jinchuriki(sp?) balance and to ensure the further safety of his village by not having Kyuubi return free and rampaging later on. So all of Madara's plans was foiled and he was forced to retreat after getting physically beaten. That is a loss to me at least.