Not that I'm saying it makes sense, Obito being Tobi, because it doesn't, till Kishi explains it.
However, I wanna add my 2 cents to this.
Obito fighting Minato in less than a year: as impressive as this feat is, its hardly far fetched or outlandish for him to do this. All he did in that fight was use his s/t to try and warp Minato in. He wasn't exactly batterring him was he, so its REASONABLE that even a chunnin like Obito with such a haxed ability, could fight Minato.
Controlling the kyuubi: All Uchiha's can control the fox, with either the shatingan or Ms. Sasuke even suppressed it with his 3 tomoe sharingan and he did so accidentally. Madara and Tobi seemed to use a sharingan when they controlled it and since kamui is an Ms technique which we had no idea was being activated everytime Obito warped, he could have used his Ms to control Kuruma, without us seeing it.
The one and only issue I have with him controlling the kyuubi is not the feat itself, but rather, that the kyuubi recognized him/chakra/sharingan. So that naturally means, before Kuruma was sealed inside Mito and then Kushina, he encountered this same chakra/sharingan/person.
I still have a feeling that when the seal almost broke during Mito's labour, it was not by accident and that an attempt was made to release the kyuubi, but it failed.
I agree with Kyf that Shisui and Obito are anomalies in a way in respect to their ms. It seems they both had the same technique in each eye, varying slightly in its functioning. This strikes me as very odd and maybe their related in some way.
Did the technique kamui exist BEFORE Obito was born? If the technique originated from him then he trully was a very special and unique Uchiha. Same goes with Shisui and koto. Kamui being an Ms technique, should have caused Obito to lose his vision, regardless if he has Hashi's dna, yet his eyes seem in perfect condition.
So many questions, I hope Kishi will answer them for us.