This 2008 issue of FRAMEWORK: The Journal of Cinema and Media included a lengthy interview with Jay Schwartz. It pretty much covers the entire history (and pre-history) of Secret Cinema, up to that point. It was written by Elena Gorfinkel, who at the time was a professor of film at Bryn Mawr College (and kindly invited us into her classroom to show films).
The same issue also featured an interview with Gore Vidal!
See it here: