Curse those greedy delvers! But what with? I know! How about Aurophobia, fear of gold? Or Barophobia, fear of gravity? And I can hit that annoying wizard with Bibliophobia, no more spells for him!
The TRUE origins of Magic, and dont even get me started on Prophecy.
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.