man that got really big. Sorry. I should have answered one at a time.
Except noble marrying commoner, why would a ruler care who married whom? (I understand marrying in your same area)
I understand to control the people, you have to restrict their movement, if you let them move freely, they would move to a nicer noble, and leave you with no workers.
My military does have noble leaders, but some are bascially warrant officers of equal title. The higher up the more likely to be of noble blood. I could see a general-warrant officer if he was extremely gifted in controlling troops and earning their respect and the respect of fellow officers, it would of course be an extreme rarity.
Still, sometimes, excellence–or something similar to it–will out. The King of France once turned his entire army over to a schizophrenic teenage peasant girl, after all.…