Drones mutate into the buildings they construct. The only way to stop a building from completing is to destroy it or to cancel it; in the latter event the drone is recovered and may be used for some other purpose. Once the building is complete the drone is unrecoverable.
Drones benefit from burrow. Unless the enemy brings detectors burrowing can minimize the damage caused by a raid on harvesting operations. Once the enemy is repelled harvesting may immediately resume without requiring the replacement of all workers.
A StarCraft II "Classic" skin modeled after the StarCraft drone is available for those who purchased the physical or virtual ticket for BlizzCon 2018, and will be available for purchase at a later date.