In Act 5, Macbeth receives news that Lady Macbeth has died. His reaction to her death is a resignation to the inevitability of death. This event suggests that Macbeth has become desensitized to murder and death, as he seems numb to the news of his wife's passing.
I'm guessing it's Macbeth's ability to be persuaded easily? Lady Macbeth convinced Macbeth to go through with murdering Duncan, which led Macbeth to become insane and regretful almost about what he did.
no
Macdonweald. He split him from the nave to the chops. Macbeth did not capture the Thane of Cawdor because when Ross greets him with the title, Macbeth says "The Thane of Cawdor lives, a prosperous gentleman. Why do you dress me in borrowed robes?" Had Macbeth captured him, he would not have thought that he was a "prosperous gentleman" and Ross would not have to explain to him that the former Thane was a traitor.
Act 5, scene 5. Just after Macbeth finds out Burnam wood is moving.
Exhausted
this push / will cheer me ever, or disseat me now. / I have lived long enough.
Probably (well almost certainly) Richard Burbage.
I'm guessing that you are asking two questions: "How does Malcolm feel about Macbeth?" and "What has Macbeth done to become the king?" The answer to the second question is simple: Macbeth killed King Duncan in order to become king. The answer to the first question is almost as simple: Malcolm hates and fears Macbeth. I hope your command of English is sufficient to understand this answer.
This is the answer He is unable to feel pain at the thought of death and is exhausted from all of the bloodshed.
He realizes that the murder is not a good idea and decides not to proceed with it.
When critics talk of a character being 'one-dimensional' they usually mean that he has no backstory. When Macduff (in Macbeth) says of Macbeth "He has no children" you realise that Macduff and Macbeth both have lives outside the play. (Macduff is a family man, Macbeth is not). Almost all the characters in Shakespeare give hints that they have a life outside the play - they are multidimensional.
One of my favorite passages from Macbeth is Lady Macbeth's soliloquy in Act 1, Scene 5, where she calls upon the spirits to "unsex" her and fill her with cruelty to commit the murder of King Duncan. It showcases her ambition, manipulation, and inner conflict.