So Minato can now dabble with MS Madara
As I said the victory doesn't matter, the fact that they were constantly fighting on equal grounds is more than enough
Contract with the Kyuubei is the genjutsu itself.
Even though it's pure headcanon that he can release Edo, there are 2 points to consider
1. If he breaks the contract, what stops the corpses from attacking Minato anyway, considering even killing the summoner won't do it
2. How can Minato seal Tobi, who is more talented than him to begin with, while also being pressured by edo tensei