1. Can you say a bit more about the Grand Council?

If I do it will be in the books.

2. How many men can the Greyjoys rally?

No comment.

3. How old was Jaime Lannister as he joined the Kingsguard?

15. Youngest in history.

4. Who was Ned's mother and what happened to her?

Lady Stark. She died.

Was Aegon the Dragon married with Rhaenys and Visenya at the same time?

Yes.