I'm no expert on autolands as I've not done too many myself. Most of what HPSOV says seems to ring true with what I remember. There is NO pilot input until the autopilot is disengaged on the rollout. I would also point out that the autoland does a sickeningly good job of landing the aircraft which I often find disheartening after I have done another bone-rattler in zero wind!
As for Cat 3c ops, I was told by a trainer during my CPL days that although aircraft could land with zero RVR there was a minimum requirement of 75m RVR to taxi.