Scene changes can be accomplished by moving one or two set pieces or lighting changes. Even merely exits and entrances will change scenes. It need be no more complicated than any simple production of a Shakespeare play. Fees are negotiable for productions. I would permit free use for classes, readings and workshops.
Colorblind casting is fine.
Dialects are unnecessary as the characters are often not speaking English, and when they are it would be drastically different from modern English, but that can be director's discretion. Robert the Bruce was read at the Playwrights' Center in Minneapolis on January 4, 1996. It is based on three modern biographies of Robert Bruce and on the 14th century epic poem The Bruce, by John Barbour. Anyone wanting more particular information should contact the playwright.