Of course they don't know what the Mangekyou Sharingan is. The point is that either Kakashi found another way or he holds himself responsible for Obito's death, making it the same as having killed his best friend.

As for Sasuke's betrayal, I think he has a lot on his side: Sasuke has pretty much learned everything he needs to, Orochimaru is currently bedridden, Sasuke is using a jutsu Orochimaru didn't know he had, Sasuke has the drop on him, and Kabuto has always seemed like he might eventually betray Orochimaru, so he might help in the end. Frankly, I thought Orochimaru was starting to get old and I won't really miss him. Besides, Akatsuki is far more badass.

Alec is convinced Sasuke won't be able to pull it off, but I'm not so sure. I mean, Sasuke seems to have planned this carefully. I guess we'll see.