I am for breaking up the general authority into subsets of laws, so you can have Revocation rights at various degrees, vassal warfare allowed, etc. I like it better when I can tailor my own set of laws.
I understand you can keep your dukes to de jure dukedoms, then the buggers marry a duchess within your kingdom and bam super dukedom! AND I HATE THAT!
This can be avoided with proper vassals management (i.e. marriages/succession control and respect of de jure borders for dukes).
Some of your ideas are interesting, but I think there would be problems trying to determine a realistic time limit for wars before the liege could intervene. Particularly in later years, even relatively small wars do take years because sieges simply take so long due to upgraded holdings and more troops to manage and fight. I think your suggested time limits are definitely too short. I would be interested to see how this impacted the balance of the game and the AI, but I doubt such drastic changes would be feasible unless they were done in steps over a number of patches. I'm not really good with history, but I suspect there would also be issues with this due to trying to maintain the realism of the game.I suggest to make gradual the ability to stop such wars :
In a lot of games you are going to lose wars especially when you get invaded or are the target of a holy war. This would mean crown authority would end up being almost impossible to maintain. Anything like this would have to only be for wars that you start and then surrender and I think even then the opinion penalty and restrictions for raising crown authority might have to be loosened a little.Also, since nobody likes loosers, CA should get weaker after the loss of major wars