Why don't the Seanchan believe in Shadowspawn? They have a blight too, even if it's not the same as the one in the Westlands so wouldn't the Empress and the Royal Family at the least know about them?

I'm at the part in book 10 where Delana says that the Ajah heads want Egwene's advisors to spy on her. Does that mean the Ajah heads in the Tower (Minus the Blues, obviously, and the Reds) or have the Rebels chosen their own Ajah Heads?

Also, I thought Egwene's month of building up was over already. Why hasn't she started the siege yet? I know she doesn't block the harbours because she doesn't want to kill the people on the ships but I thought she was going to do what Arymilla is doing to Caemlyn.