As part of Audra McDonald’s duties as winner of the 2018 Eugene McDermott Award in the Arts at MIT, the Broadway great — can you believe she’s won six Tony Awards? — sat down with Oskar Eustis at MIT’s Huntington Hall over the weekend. The McDermott Award Gala was held afterward at Walker Memorial at MIT. The prestigious award comes with a $100,000 cash prize and a residency at MIT. The conversation with Eustis touched on all aspects of McDonald’s incredible career, including her memorable 2011 portrayal of Bess in “The Gershwins’ Porgy and Bess’’ at Cambridge’s American Repertory Theater before the show moved on to Broadway.