It's sorta like a judge not insisting on being called "your honor" at home at the dinner table. The Marshal title is only relevant when talking about military matters with the army.
Roughly, yes.
Marshal is a minor title, unlike landed nobility or government positions. Guild titles, for example, also only show up when you message the guild. Likewise, the marshal title shows up when you message the army (and soon at least one more military channel).
