“Andrew Garfield, a Tony Award nominee for playing the defiant Prior Walter in the Broadway revival of Angels in America, was 9 years old in 1993, when Stephen Spinella won the first of his two Tonys in the role. As it happens, Mr. Spinella is again tackling the furious, fantastical poetry of Tony Kushner’s two-part, seven-hour play, this time as the bilious lawyer Roy Cohn at Berkeley Repertory Theater. The New York Times asked the actors, who have never met, to correspond by email during a week’s worth of shows. … Below are edited excerpts from their exchange, which included insights on how to understand the character of Prior, a man with AIDS who accompanies an angel to heaven, and how to maintain the stamina to play him.”