Short answers, pulled from the story.
The earliest known use of the term virtual reality in print appeared in 1958 when The Theater and its Double translated Antonin Artauds phrase la réalité virtuelle. This publication marked the first instance of the English translation appearing after Artaud wrote about the concept in 1938.
Harvard Professor Ivan Sutherland created The Sword of Damocles in 1968 with help from student Bob Sproull to serve as the first HMD for immersive simulation applications. This heavy system had to be suspended from the ceiling yet featured simple wire-frame model rooms.
Motion sickness eyestrain headaches and discomfort remain most prevalent short-term adverse effects affecting approximately 25 to 40% of users. Women are significantly more affected than men by headset-induced symptoms at rates around 77% versus 33%.
Facebook purchased Oculus VR in 2014 for what was stated as $2 billion though later revealed figures reached $3 billion. John Carmack presented the Rift at E3 video game trade show in 2012 before the acquisition occurred.
Virtual reality exposure therapy treats anxiety disorders like post traumatic stress disorder and phobias through controlled virtual environments developed during the 1990s. Simulated VR surgical environments were also first developed in the 1990s under expert supervision to provide repeatable training at low cost.