Comment specifically on the wealth of imagery that contributes to the atmosphere of violence in the play.
You're right: there is a wealth of imagery which Shakespeare uses to create an atmosphere of violence in the play. It is sprinkled artistically throughout the play--one of the first places we see it is in Lady Macbeth's speech about Macbeth's weakness and how, if she had known about it, she would have plucked her child from her breast and dashed its head on the floor. Infants are universally helpless and cute. In this play, they represent the small and pitiful. Breastmilk (and Macbeth being "too full of the milk of human kindness") represent humanity and sympathy. The image she projects in her speech negates all of these natural human feelings which lean toward tenderness and kindness. Don't forget about all the references to sleep and sleeplessness. Macbeth hears the cry, "Macbeth will sleep no more" "Macbeth has murdered sleep"--he murdered Duncan, the innocent sleep, and because of that, his sleep will also be interrupted. Lady Macbeth also sleepwalks. There are also innumerable references to blood, sickness, and illness throughout the play. Blood begins in the battle with "what bloody man is that?" to represent war between the good and evil in the country. Then there's the blood of Duncan and how Lady Macbeth can't get her hands clean. Scotland is also repeatedly referred to as mourning, bleeding, and crying--especially after Macbeth takes the throne.