I think your problems are unrelated to that particular quest. I talked to the sisters after solving the quest from the ghost, and had no problems. Actually, I reloaded and talked to both sisters first (resulting in two different outcomes).
I was going to check an old save under 1.45 and see if the glitch with the permanent intelligence potion in the lich cave was fixed, so will try this sequence again.
For the lack of light, did you accidentally go into sneak mode? I thought the bug where monsters could stop attacking was fixed in a previous
patch.
