Short answers, pulled from the story.
Richard Bohringer became the first human to be digitally cloned and animated by a computer in 1993. Didier Pourcel and his team at Gribouille studio achieved this feat by recording Bohringer's body and face movements using nascent technology.
Systems typically used between 2 to 48 cameras, though some advanced setups employed over 300 cameras to reduce errors like marker swapping. These systems could capture large numbers of markers at frame rates ranging from 120 to 160 frames per second.
Andy Serkis became the first actor to have his performance streamed in real-time to a computer-generated skin while playing Gollum in The Lord of the Rings: The Two Towers. This technique allowed directors to see the actor's performance as it happened rather than waiting for post-production.
Purdue University houses the world's largest indoor motion capture system known as the Purdue UAS Research and Test facility. This 600,000 cubic foot facility is equipped with 60 cameras that can track targets with millimeter accuracy.
Markerless systems use computer algorithms to analyze multiple streams of optical input and identify human forms without requiring subjects to wear special equipment. These systems can break down human forms into constituent parts for tracking and utilize RGB-D cameras like the Kinect to capture 3D human motion in real-time.