'Llaewyn the Fair she was in her youth, in all truth a lover of mine. Though that boast is not mine alone, she was the beloved of many. And joyous, most joyous in form and deed. Till the time of her father's death. She alone sat by the auld king's bed and soothed his fevered brow though ever cruel in life was he. Cruel to all but Llaewyn to whom he gave every comfort and protection his world had to offer. The Fair One walked into the chamber of his last breath and the Black Queen walked out.' -Spectre of the Courtier
When the Caliph-Emperor of the Dunes hear about his son's heart attack at the northern front, his rage is unstoppable. For his son was only nineteen years old, and a trained athlete. Grief stricken as only a parent bereft of their child can be, the Emperor finally rouses the Empire into action.
So, when reinforcements finally arrive to the beleaguered veterans at the front, they are accompanied by the the Imperial Necromancers in their gold laced red silken robes, as well as the three old triplet hags of Devananon, seers and prophets who use narcotics to enhance their trance visions.
As the Prince's corpse is carted to the Spires of Devananon, where the necromancers and the triplets will work their magic, the PCs will have to conjure a plan of their own. For they are to blame for the Prince's death.
This plot is set five months after the happenings of "A Dark Moon over Sagranz", but could be adapted by any GM to fit his setting and need.
A possible answer to what happens to spells when a mage dies. If the spell is strong enough, say and enchantment or other permenant effect, part of the mages spirit may become lodged in the magic. It may be a way for items to gain some kind of intelligence, but a mage who has knowledge of this fact would be very hesitant about enchanting anyone or thing. He might have other plans for his afterlife than counting the change in your bag of holding.
Preists, I think, would have this sort of thing covered.