What will the second players duties be other than manning weapons? Why will it better to run this ship with two players rather than solo?

Turret-controls - If all the weapons are slaved to the pilot, you really lose out on the massive coverage arcs the wing-tip Omni-Orb turret offers the ship. So whether in combat, working scanners, or working as a news-reporter, every variant was planned from the ground up to have dedicated second-seat gameplay available.