I'll fill in the rest. Predators masks house a compact refractive lense for amplifying (zooming in) & viewing the environment through different spectrums (vision modes). their EM (electromagnetic view) targets xenomorphs, their thermal view targets humans & their tech view targets technology. Their masks also house a directional microphone to record & playback sounds (vocal mimicry).
Their plasmacaster is also optically linked to their mask through the attachment tubes, this allows predators to direct their plasmacaster fire through head movement alone, which is why the caster always aims in the direction that the predators mask-mounted laser sight is aiming. Finally, their mask, aswell as providing breathable atmosphere in foreign environments & underwater, houses internal mandible triggered controls which can be used to activate their cloaking, or fire the plasmacaster without touching the controls on their wristgauntlet.