What is an analysis of the text of Act I, Scene 3 (lines 111-155) of Macbeth?

Because it is a drama of such a hallucinatory intensity, Shakespeare's Macbeth has been called a tragedy of the imagination (Harold Bloom). By his own admission, Macbeth's thoughts and imaginings overwhelm him, driving him to the commission of premeditated actions.
In Act I, Scene 3, the three witches discuss their plans to cause Macbeth much unrest as they await his and Banquo's arrival. In lines 111–155, Macbeth is both seduced by the pronouncements of the witches and frightened by their menacing natures. 
When Macbeth and Banquo encounter these witches, the greetings to Macbeth confuse him. The first witch calls him by his current title, then the second witch addresses him as Thane of Cawdor, and finally the third witch says, "All hail, Macbeth! that shalt be King hereafter!" (1.3.50) Finally, they foretell that Banquo will not be king himself, but he will beget kings.
Macbeth wants the "imperfect speakers" to tell him more and explain how all that they have said can be. Soon, however, Ross and Angus, two noblemen of Scotland, ride up and greet Macbeth, reporting that the king is delighted by Macbeth's valor and success on the battlefield. Further, Ross says that his admiration contends with his desire to praise Macbeth (1.3.93), but it is their duty to bring Macbeth to the king with the pledge of a greater honor. Finally, Ross reports to Macbeth that the king bade him to address Macbeth as Thane of Cawdor. 
Ross's words baffle Macbeth because he knows that the Thane of Cawdor lives. Angus then informs Macbeth that the Thane of Cawdor is a traitor who conspired with the Norwegians, and he has been stripped of his title and sentenced to die. Hearing this, Macbeth turns to Banquo and asks him if he does not now want his sons to be kings since the witches' prophecy about him has been proven true. But Banquo cautions Macbeth that "the instruments of darkness" (witches) often reveal part of a truth in order to seduce men and lead them to their destruction in the end (foreshadowing).
Banquo's words go unheeded by Macbeth, whose imagination has been stirred by the two truths told, and just as Banquo has observed of others, Macbeth is seduced by their predictions. It is at this point that the tragedy of the imagination begins in Macbeth. He begins to contemplate becoming king since the other title (Thane of Cawdor) is now his. Macbeth wonders why he covets the title of king: "Present fears/Are less than horrible imaginings" (1.3.141-142). Macbeth considers that he may have to do nothing and fate will simply take over. And yet, he is frightened by the blurring of reality and fantasy--"And nothing is but what is not." (1.3. 145 )
It would seem that Macbeth's tragedy of the imagination has begun: on one hand, he feels that his ability to act is stifled by his thoughts and speculations; on the other hand, he considers murder, and then he thinks that he may not have to do anything as fate will simply aid him:

Come what come may,Time and the hour runs through the roughest day
(1.3.152-153).

In other words, what is going to happen is, one way or another, going to happen. But, in truth, Macbeth's thoughts are running away with him as reality and fantasy are merging in his mind--as he has admitted in line 145. 
 
Additional Source: Bloom, Harold. Shakespeare: The Invention of the Human. Riverhead Books. 1998.