Starting with TNG you had commanding officers wearing red probably to lay to rest the classic trope of the redshirt always getting killed so maybe the idea of the goatee was the same or Avery Brooks just wanted to get back to the look he had in Spenser: for hire. Either way, he looks far better with that and the shaved head.
He was a commander before becoming captain as you’ll see from the 3 pips he was wearing up until then. The station can kinda move using thrusters but it’s not designed to, they moved it to the wormhole in the pilot episode but I don’t recall it moving any other time because it’s a bit dicey. Also, the defiant can’t fit inside the station, it’s usually docked to the outer ring.
