The long hair argument is ridiculous. You're making it sound like the Kyuubi attacked the DAY Obito 'died' as opposed to about a year later. Plenty of time to grow his hair out.
And it wasn't Madara. He's shown no sign of kamui use in his fight with the Kages. And as I've said before, each pair of eyes has it's own specialization. Madara's specialization is an absolutely complete and stabilized Susano-o thats power rivals that of a Bijuu.
MAYBE someone has possessed Obito's body. But all we knew of Obito was from Kakashi's point of view. We just saw stuff from Obito's and he didn't look particularly fond of Kakashi, nor anyone else. Besides Rin. I'm entirely convinced the only reason Obito gave his eye to Kakashi was because he believed he was going to die and so that he could, in some way, help keep Rin safe.
The bitterness of unrequited love and the death of Rin, along with being shown up by Kakashi in every way, including earning Rin's affection, could have easily turned him into a very bitter and angry person.
EDIT: And his hatred for Konoha? Easy, they clearly didn't even try to recover his body to bury/burn properly. He probably took it as a sign that they didn't really give a ***about him.