How and why did Macbeth change from war hero to villain in Act 2 and 3? What is the stagecraft used? Historical background?
I can help you with answers to parts of this question concerning Shakespeare's Macbeth. Macbeth changes from war hero to villain by assassinating the king of Scotland. He is ambitious anyway, but when witches predict that he will be lord of a new castle and be the king of Scotland, too, Macbeth wastes no time in figuring out how he can make this happen. He realizes that there is a chance he could become king without his doing anything to hasten it, but when King Duncan officially names his elder son his heir to the throne, Macbeth decides not to take a chance on waiting. His wife, Lady Macbeth, is just as anxious for him to be king as he is, so she plans the assassination and, although he has second thoughts, he carries the plan out.
Historically, Macbeth battles with Duncan for the thrown and actually rules Scotland for much longer than he does in the play. There was actually no assassination. Incidentally, Banquo's heirs really do rule Scotland for generations, and James I, the reigning monarch at the time Macbeth was written and first performed is a descendant of Banquo.