You can't request a civ to change its civics if it has changed in the recent past. It works the same way as for you i.e. a couple of turns after a revolution, you can't change civics. You can't trade away your cities to your vassals. The only exception is if it causes revolts, I think. (However, I agree that you should be able to trade away core cities, or your vassal shouldn't collapse due to that. Maybe core cities held by master should count as vassal's for vassal stability?). The penalty for central planning makes sence. If you are forced to live with outdated civics, then wait some turns more. Historically, communism was adopted 70 years after it was invented. The war penalty is based on war wareness AFAIK. Even if you win your soldiers want to go back to their homes, and they don't want to die in the field.