He does not know how to fight, craft, or hunt. He can farm a bit, he knows how to raise animals, and he knows how to cook anything. He doesn't build much, as he has a kitchen built for him by expert masons and carpenters.
His presence in the castle is not unusual, and should be expected. He has a home in the castle, but does not live there.
He was hired by the King and should be paid (the King may decide the fees granted to him).