Answer:
Europeans carried a hidden enemy to the Indians: new diseases. Native peoples of America had no immunity to the diseases that European explorers and colonists brought with them. Diseases such as smallpox, influenza, measles, and even chicken pox proved deadly to American Indians.
The witches are the ones who give Macbeth the prophecy that he will one day become king, that Banquo with father kings, and that Macbeth can not be killed by anyone born of woman. These set off Macbeth's entire journey in the play and motivate him to kill the king, kill Banquo, and ultimately lead to his downfall.
I am not sure what section you are referring to but probably because the sun is a star.
The significance is that he wasn't willing to let go of his chances of trying again. "They dragged Robert out the door, knees stiff, feet dragging."
