Now the next part that I really feel like houseruling, the other spellcasting classes of Wizards and Illusionists. In a lot of ways I welcome the return of the Illusionist base class as I'm not so keen on the use of specialist schools of magic as in 3e to create an illusion or necromancy specialist Wizard. I am tempted to add a specialist Necromancer base class to my C&C game with obviously adjusted spell lists and some specialist class abilities.
My main thoughts are similar to those about clerics in having schools of magic replacing the domains of the clerics, but using constrained spell list though C&C has considerably less spells than say D&D plus splatbooks, but it would not be hard to convert over spells from other sources than the core C&C PHB.
Types of wizard apart from the aforementioned Illusionist and Necromancer could include a conjuror, diviner and evoker. This then requires the meaning of these types to be clear and different enough to give some flavour and reason to use these rather than the base spell lists. More of that in a second part to this post.