2. The three prisoners, who were not Michael Burnham. Either they were fake prisoners to shape Burnhams narrative for Lorca, or they are being sent to the worst jobs on that mining colony to die quickly, or they are not going to a mining colony at all, but a dentition facility where they can't say anything about the Discovery or the "final" fate of Michael Burnham, until the experiment or the war is over.
I assumed those prisoners were killed in a shuttle “accident” on the way to wherever they were going. That’s why Saru’s antennae extended in the mess hall as they were leaving because he sensed their imminent death.