Sortiliena Serlut=Asuna in kirito's mind
Not at all. She's a resident of the Underworld. Asuna looks the same in Underworld, but with pretty cool clothes.
No way. Don't even consider that idea
The idea is not bad, but good of the little that is updated the Information of the Volumes of 15-18 of the Light Novel, Liena comes out with Alice and Asuna.
And this occurs in Volume 16, which is during War of Underworld