Well, about the seals and the madness (just to get it out of the way), I believe that if the seals are broken, Saidin will burn off the taint and no madness or rotting will progress. However, those already mad will remain mad. I don't know who exactly ordered Fel killed, or why I also don't care. What I wonder about is WHY KILL HIM WITH A GHOLAM? A grayman or even a Dragkhar or fade would have served. Aside from Fel's knowledge, which was solved by a simple killing, what was so significant about him?