Technically, no. There are 2 states, the first where he looks mostly human and then the second where he appears totally inhuman with wings. In the fight with Itachi the white snake emerged from Sasuke's body because he exhausted his chakra and tried to use more. But don't confuse that with a third state.
he did after sasuke's match in the preliminaries, but sasuke willed it to unseal.. relying on its powers
You can't it was removed from the game but the model still in there make guy do primary Lotus to u with sasuke u will see him with curse mark same with Kakashi but u see his Eye
Well I'm sure most shinobi of Konoha in Kakashi's generation knew about Orochimaru before he became a traitor. Note that Anko is around Kakashi's age, and he turned against the village and gave her the curse mark before leaving (as Orochimaru was Anko's teacher). So it's likely that Anko, as well as Kakashi and others in their age group, knew of him before he became a traitor.
Itachi doesn't have curse mark. Its just Sasuke
You need curse mark mark rampage
There is no curse mark level 3. There's only 1 and 2.
Sharingan, Mangekyo, Curse mark level 1, curse mark level 2, curse mark level 3, Full curse(this is where the dragon is released from saskues body
Kimimaro's curse mark is the seal of heaven, just like Sasuke's
Well, Sasuke's curse mark is real to HIM. Its not real in this world but of course in the world of he ninja the curse mark is a curse placed by Orochimaru to further advance a certain seal of dark jutsu.
No.
no
Nope.