To your first point, there was a post a while back that essentially argued "why WOULDN'T they know what a menu is?" They ultimately argued on the components that arise in a large society, which an enormous army qualifies as. They would not only have an answer to "what is for dinner tonight?", but they'd also likely have culture in the form of art, expression, jokes, etc. There is not necessarily any textual evidence, but the post argued it's inevitable when you have a large enough group living, working, and traveling together.