Make sure it reflects that you had control of a performing band in it's preparation and presentation.
It would help if it reflected responsibilty for portions of the marching presentation.
Being the consumate subordinate is good as an assistant, but they need to see that you can take the reins and control the results.
Standard questions pertaining to budget, purchase decisions, fiscally responsible.
organization of the facility and all of the connected details. organization of subordinate staff that will be productive.
Unique questions, but still important: how you relate to other faculty, parents, and community leaders.
Emotional stability of the progam and vision for development.
Sometimes you'll get the one year, five years, ten years question.