I wouldn't worry about Raphael too much. There is no way a cambion, even with the crown, would be able to become ruler of the 9 hells. If it were that simple, Mephisto had done it himself.
As for the rest, try letting Orpheus becoem a mindlfayer next time, no problem relly with that .
And Astarions quest you can reach from an entrance in the city wall in teh middle of the lower city map.
