The unnamed child who projectile vomited on stage at Lincoln Center's run of "Our Town" was Shane Culkin. This was confirmed by his famous brother Macaulay Culkin on Marc Maron's WTF Podcast.
The Broadway production opened at the Vivian Beaumont Theater on January 21, 1991 and ran for 16 performances.
The title refers to the enormously long autobiographical novel that Spalding Gray describes trying to finish, a manuscript of which he uses as a prop throughout the movie. The same year the film was released, this was published (apparently in edited form) as "Impossible Vacation".