Short answers, pulled from the story.
Cliff Eisen is a Canadian musicologist and Mozart expert born in Toronto on the 21st of January 1952. He specializes in the Classical period, particularly Mozart and performance practice. He was based in the Department of Music at King's College London.
Cliff Eisen wrote extensively on authenticity questions surrounding the works of both Leopold Mozart and his son Wolfgang. His publications also cover Mozart's chamber music, life in Salzburg, biography, and Mozart's representation in contemporary documentation.
Cliff Eisen studied at the University of Toronto and then at Cornell University. He taught at the University of Western Ontario and at New York University, and was based at the Department of Music at King's College London.
Cliff Eisen was terminated by New York University in 1997 after a student filed a lawsuit against the university alleging sexual harassment. The university had previously reprimanded him following complaints from four other students.
Yes, Cole Porter appears in Cliff Eisen's bibliography alongside his Mozart scholarship. His primary body of work focuses on the Classical period, but his publications extend to the American songwriter as well.
Performance practice is the study of how musicians in a given historical period actually interpreted the works of their time. Cliff Eisen includes this as a central strand of his research on the Classical period, alongside his work on Mozart authenticity.