I don't know much about the hats and uniforms but taking a quick look through the Time Life "Arms and Equipment" I see a red Confederate artillery kepi with crossed cannon and "W A" for Washington Artillery (New Orleans), it is also present in period photographs. There is also a "13 Va Co H" on a forage cap that belonged to private Kennedy Palmer. There is another blue LA militia unit kepi later with "C.G." on it but it is not clear which company it refers to. In looking through period photos of whole companies in at least one I see some blurred lettering on the front of every kepi. Folks seem to have been inclined to wear the initials of their companies nomme de guerre, but not the alphabetic company designation.