If it's Izuna then he would know about Kakashi. Obito doesn't make sense, he saw Kakashi as a friend and his last 'dying' act was to give Kakashi his Sharingan as a token of their friendship and his desire to be helpful. To think that would turn in to such bitterness which would involve Obito going under cover, bringing together the world's worst/most powerful ninjas and obtain control of the Kyuubi due to some irrational childish angst seems unrealistic.
With regards to Naruto's powerup, I don't see how it is remotely useful given Kakashi is the one who holds the key to defeating Taobi with Kamui. With Kamui, a simple kunai would be enough to kill Tobi let alone an uber Kyuubi powered up Naruto.