How will restocking ammo work? Do we need to bring it to a landing pad, or will there be future resupplying ships and ground vehicles? Will the Vulcan be able to repair and rearm the Ballista?

Currently, the Ballista needs to be taken back to an outpost, where it can be repaired and rearmed. In the future, dedicated rearming and repair vehicles (such as the Vulcan) can be used to support any ground vehicle, including the Ballista.