Having Minor Factions act like the Majors (but perhaps not expanding city number, etc, and just build up their one city) sounds great.
The spellbook change is another thing. It's a very big change. There's a lot of very big changes. May I suggest not rushing in and making very big changes piecemeal, but instead take some time (fixing stability and the other things will keep you busy for a while) and consider all the potential very big changes as a group?
If you're doing that already then never mind, but if you're 'hot to trot' on fixing things, remember the US Navy Seals mantra "fast is slow, slow is fast".
“Fast is slow. Slow is fast. Watch your fields of fire, pick your targets, aim centre mass, squeeze the trigger. The faster you go, the more mistakes you make. The more mistakes you make, the deeper in the shit you will be. Go slow. Try not to make mistakes. Be one with the battle yet transcend it. Float above the action, survey the scene, target immediate threats, and dispatch them with ruthless efficiency."