Magic ... a way of life
I have read through the prior posts, and the mechanics that you have outlined are by far the best I have seen. I do have a suggestion (humbly submitted) for the balance problem. Use the aspects of roleplaying. In other words, cap what the players can buy in the beginning, and force them to seek out the new skills. Maybe limit the number points that can be expended on various types of spells (offensive, defensive, transport etc.)
If all the players are warrior mages I think you might lose some diversity of play. Some players (and NPCs) might get the quick bang if a swordmaster is easier to find then Wizard who is willing to take an adventuring student.
In the campaign that you are creating are some schools more difficult to locate then others?
I am definitly intrigued by the mechanics you have set forth.