Obito, who knows all about everything in the whole damn Narutoverse thanks to Madara, and who knows all about Yin, Yang, Yin-Yang and Izanagi doesn't know sh-t about Izanami? Shame on you, son.
Itachi fought a legit battle against Sasuke. He wouldn't have survived if he hadn't fought seriously. He just didn't actively try to kill Sasuke, but he was convincing enough for Sasuke to be in denial over it. Regardless, Itachi wouldn't have a choice.
Obito knows about Kotoamatsuki, he wouldn't let himself be caught by it. As soon as he'd see the crow, he'd Kamui it away.
Yes, by himself, after he resealed all the bijū. Read the f-cking manga, you dolt.