Concerns about running a kingdom

So I just got my kingdom running (sort of). I took it over from Vaegers and assigned castles and towns to some companions.

Don't really know what I'm doing, so I did some research. Turns out, I assigned feifs to the wrong companions there...

Also, I'm having some trouble with right to rule.

I was wondering if anyone can elaborate on a few things to help me out:

• Right to rule. Every time I want to send a companion on a quest for me, s/he says that another companion was sent out and it's probably better to wait a while
• Vassals. I know how to create them, but how do I strip one of my vassals of their title - kick the out so to speak?
• Feifs. Assuming someone in my kingdom is a vassal that I like, how would I remove their feifs from them (essentially, give them back to myself)?

Any assistance will be greatly appreciated