Thanks for the feedback and interest.
Ensing Tillman's main job is shuttle pilot, but as a junior officer, she gets training in other jobs she'll need to know as she moves up thru the ranks. It's not like they fly shuttles all the time. Don't worry, she gets to fly one soon; if I don't change the story in my head before it gets on the screen.
The tactical officer is in charge of the tac-team, but the Marines are filling that role. The problem with losing the tac-team is it's mostly made up of boatswain's mates, people that can be put to work doing routine maintenance. About the only additional duties the Marines can fill is kitchen patrol.
Uniforms would be TOS, but with an option for women to wear pants (required for away team missions).