Banquo's ghost appears in act 3, scene 4, and sits down in Macbeth's place. The fact that Banquo's ghost chooses to sit in the king's seat is significant because it foreshadows how Banquo's descendants will inherit the throne, as the witches predicted.
I dont know why she wants jig to stop talking but I imagine she says it over and over again to show that she is aggrivated and to make her point to show that she wants him to stop talking.
