That’s a good idea but I think only the first idea falls under “formation” (-stay together & attack together)
the rest seems more like a specific orders for attacking and defending. “Formations” should be for example melee units in front while ranged are in the back, and sense ranged are already planned to be in the game.
I’d even appreciate a ‘pre-feature’ for this - I think the Hearthlings should make an effort to re-form to a group before hauling off to their attack/rally location…
I also noticed that often footmen wont leave a defend location to go after an archer attacking them.