…and when he reads about your performance in the fight against the rebels, he’s so full of wonder and praise he can hardly tell which belongs to you and which to him.

Ross is exaggerating for effect–but with the unconscious irony that Macbeth ends up being highly unworthy of the king’s praises.

In other words, messages rained down on the king as thick as hail, and every one brought praise of Macbeth’s valor in battle.

Messages come “thick as hail” in Macbeth also; it’s a play full of letters and news, mostly ominous. See note on “What is your tidings?” in 1.5.

sightless substances: invisible forms. (Lady Macbeth is still addressing the “spirits” or “ministers” that bring murderous thoughts.)

wait…mischief: serve nature’s evil purposes.

compunctious…nature: natural pangs of conscience.

fell: dangerous or fatal. Compare the famous phrase “one fell swoop” in 4.3.

In other words, the witches addressed Macbeth as “Thane of Cawdor” just before he was promoted to that title–and also addressed him as king-to-be, suggesting that the crown lies in his future. (See Act 1, Scene 3.)

“Referred me to the coming on of time” means “pointed me toward future events.” The relentless “coming on of time” will become the idea that haunts Macbeth in his “Tomorrow and tomorrow” speech.

Which: refers back to “the night’s great business.”

Lady Macbeth fantasizes that killing the king will give her and her husband absolute control over their futures. Again the dramatic irony is intense: political power isn’t the same as power over fate–the kind the Witches seem to exercise (or at least to be allied with). Soon the future will become an intolerable burden for the Macbeths; see “Tomorrow and tomorrow” in 5.5.

To make the event go smoothly, act in a way appropriate to the event: be welcoming in your looks, your handshake, your conversation.

beguile: make [the time] pass pleasantly (but also with a suggestion of deceiving).

Lady Macbeth urges her husband to play the perfect host during “the time” of Duncan’s visit, so as not to give away his evil intentions. Her word choice is ironic: by the end of the play, time seems to have become Macbeth’s enemy, playing a dirty trick on him as it leads all of us “the way to dusty death.”

The guilty Macbeth imagines that the unknown “hands” knocking at the door are punishing him for his crime by plucking his eyes out. (In fact, the person knocking–Macduff–will kill him at the end of the play.)

The image of punishment by blinding links Macbeth with King Lear, in which Gloucester’s eyes are plucked out onstage in a famously brutal scene. It also links Macbeth with another tragic hero, King Oedipus, who punishes himself in the same way. (One great playwright calling back to another…)

In “‘What Hands Are Here?’ The Hand as Generative Symbol in Macbeth” (1988), Kathryn L. Lynch emphasizes “the important, even pivotal role that hands play in Macbeth,” noting that this is one of 32 major references to hands in the course of the play. (More at JSTOR.)