Dark Heresy 2e Core Book p. 215. The power Puppet Master has "Special" listed under what it takes to sustain it. The text includes no mention of sustaining the power, only that the psyker must divide his actions between himself and the victim.

Barring suicidal commands, is the victim just a puppet until he is out of range?

It is sustained until the power is no longer sustained, voluntarily, or broken.

Yes. It says " Additionally, the power breaks as soon as the target is out of range. "