In the final battle, human space fleet approaches the enemy planet, and most of the ships are sacrificed in a tactical maneuver. How many people were on these ships, and what was their role?
Just saw this movie not long ago for the advanced screening. Its seems that thousands were killed in the battle as Ender was made to believe he was in a simulation but he actually wasn't. Harrison Ford states that thousands were necessarily sacrificed in the battle.
In the movie, the small fighters are actually indeed drones controlled by the pilots at Ender's side. However, as Colonel Graff reveals, "We lost a thousand men on the transporters you abandoned!", the Transports do indeed have personnel onboard if only in minimal amounts. Also, if you notice when Ender is giving commands, he refers to the collective as a "Battle Group", and he orders them to deploy their drones, implying that the carriers and dreadnoughts themselves are not unmanned.
During the film, the fighters were referred to as drones. Hence them acting more like a swarm. However, the transports, which Ender ordered the drones away from, were manned. I believe they mentioned thousands died on the transports.