What is Macbeth like at the start of the play and how do we feel about him?
At the start of the play, Macbeth is a good man who knows his place. He is a loyal servant of the King. God appoints the King to rule. If the King rules well, then his subjects will love him and he will reward their love with gratitude and generosity. This is the ideal state of affairs at the start of Macbeth, though just before it, there has been a rebellion, and the play opens with an account of the defeat of the rebels.
Macbeth is a hero at the beginning of the play. He fought so bravely that King Duncan awarded him the title of Thane of Cawdor after the former Cawdor proved to be disloyal. The men talked of how well Macbeth performed to the king, which is why he gave him the new title.
In Act I, scene 2 the Captain says "For brave Macbeth--well he deserves that name--disdaining Fortune, with his brandished steel, which smoked with bloody execution, like valour’s minion carved out his passage till he faced the slave; which never shook hands, nor bade farewell to him, till he unseamed him from the nave to th' chops, and fixed his head upon our battlements."
The King calls Macbeth a "valiant cousin! Worthy gentleman!" Because of this, we see him in the same light. We don't see any ambition or vengeance in him at all. He is just a great fighter who sacrificed himself for his king and country.
How does Macbeth react to the witches predictions and what does his reaction tell us about him?
It doesn't take Macbeth long to have the thought of murdering Duncan cross his mind. Around line 133 of Act 1, sc. 3, upon hearing that he has just been given the title Thane of Cawdor as the witches predicted, he says, "The greatest is behind." This means that the next prophecy, that of being king, is the greatest prophecy and it is next in line. Less than 20 lines after that he says, in an aside of about 16 lines, that what he's heard so far shows that the witches speak...