DiMarco's oral histories include Tower Stories: An Oral History of 9/11, which chronicles the September 11 attacks in 2001, from diversified perspectives on the destruction of the World Trade Center. The book features a foreword from former Governor of New Jersey and Chairman of the 9/11 Commission Thomas Kean, who praised the book for being as important as the Federal Writer's Project under the Roosevelt Administration and the Works Progress Administration Slave Narrative. Tower Stories was also praised by William F. Buckley. Senator Bill Baroni of the New Jersey Senate called Tower Stories the "perfect supplement to the 9/11 Commission Report," noting that DiMarco's oral history provides human and emotional context to the Commission Report's stark factualization.

DiMarco has appeared as a television and radio guest for 9/11-related events, notably on CNN, Premiere Radio Networks, and the National Geographic Channel.

Other oral histories include Heart of War: Soldiers' Voices from the Front Lines of Iraq, a collection of first-person narratives from U.S. veterans of the War in Iraq.

Critics of DiMarco's oral history work praise the respect he pays to his interviewees. They note the diversity of perspectives he brings to bear on a single issue. His interview subjects are often highly-intelligent people whom mainstream media have failed to notice. DiMarco himself has voiced dissatisfaction with mainstream media.

DiMarco wrote The Actor's Art & Craft with Bill Esper, one of the "most important contemporary master-acting teachers" in the United States. Esper founded the William Esper Studio and the Professional Actors Training Program at Rutgers University's Mason Gross School of the Arts.DiMarco has been called Esper's protege. The Actor's Art & Craft details how Esper explores and elaborates on the famous acting techniques pioneered by legendary acting teacher Sanford Meisner. The book features a foreword by David Mamet, who studied under Esper at the Neighborhood Playhouse; it has been endorsed by Meisner-trained actors such as Sam Rockwell, Patricia Heaton, Mary Steenburgen, and Calista Flockhart among others.

The Quotable Actor collects 1001 quotes from actors on such diverse subjects as imagination, rehearsal, technique], and the actor's lifestyle. Featured quotes come from diverse sources including Constantin Stanislavski, Daniel Day Lewis, Ellen Burstyn, Paul Newman, Jack Nicholson, Stella Adler, Forest Whitaker, Laurence Olivier, and many more.

DiMarco collaborated on Out of Bounds, written with Roy Simmons, a former offensive lineman for Georgia Tech who went on to play for the New York Giants and took the field in Super Bowl XVIII for the Washington Redskins. Simmons became the first former NFL player to publicly announce that he is HIV positive, and one of the first to reveal the extent to which drugs and alcohol backdrop the world of professional football. Following the release of Out of Bounds, Simmons caused controversy among the gay and lesbian community by publicly stating that homosexuality is "against God's will."

In late 2009, DiMarco announced he was writing a book with a noted Chinese political dissident, Tang Baiqiao. The project will cover events surrounding Tang's life, including his experiences at the Tiananmen Square Protests of 1989, and after.

DiMarco has acted in regional theatre and lists television and film roles on his acting resume.

DiMarco attended Steinert High School in Hamilton Township, Mercer County, New Jersey where he served as President of his senior class.

He earned a double Bachelors Degree in English Literature and Theatre Arts from Drew University, and delivered the commencement speech for his undergraduate class alongside Olympia Dukakis, who was being honored that year.

DiMarco went on to receive his Master of Fine Arts degree from Rutgers University Mason Gross School of the Arts while studying acting under Bill Esper of the William Esper Studio.

He has taught in the Theatre Arts department at Drew University, and at the New York Film Academy.