"Let me have men about me that are fat, Sleek-headed men, and such as sleep a-nights."
Act II: Scene i
"It must be by his death;..."
Act III: Scene i
"Et tu, Brute?"
In this depiction, Caesar is talking to Antony. Caesar says to Antony, "Let me have men about me that are fat, Sleek-headed men, and such as sleep a-nights." (I:2:Ln 192-195). Caesar says this to Antony, referring to Cassius as having a "Hungry look". Later in the book/play we see he wasn't wrong as Cassius gathers a band of fellow-minded men and stabs him. Antony speaks up for Cassius, saying he was a good roman.
Act IV: Scene iii
"...thou shalt see me at Philippi."
Here, Brutus is walking in his orchard, musing over what Cassius has said. The quote "It must be by his death;..." (II:1:Ln 10) is the beginning of a much longer monologue by Brutus. In it, he talks/thinks about what is to be done about Caesar. He reveals that he is a friend of Caesar and has no reason to hate him personally. But he decides Caesar is dangerous to Rome.
Act V: Scene iv
"This was the noblest Roman of them all."
"Et tu, Brute?" (III:1:Ln 79) translated from Latin it means "And you, Brutus?". Caesar thought Brutus was his friend, then Brutus stabbed him. Most people don't stab their friends. So Caesar started hunting Brutus as a ghost. Quis te agnus dei vocant?
"O Julius Caesar, thou art mighty yet!"
The complete quote from Caesar goes, "To tell thee thou shalt see me at Philippi." (IV:3:Ln 283). After Caesar's ghost tells Brutus this, he decides they will go to Philippi as soon as possible. A ghost saying they will see you somewhere is almost always foreshadowing your death. So Brutus goes of course wants to go with all haste.
"This was the noblest Roman of them all." (V:4:Ln 68). Brutus in his trusting manner dies. I blame Cassius. Antony says that, even though Brutus did the wrong thing, his heart was in the right place. His heart was with Rome's people, trying to help them.
"O Julius Caesar, thou art mighty yet!" (V:iii:Ln 94). You know, they say the road to hell is paved with good intentions. Brutus had good intentions, but it was a bad thing to do and he paid for it. So end the Tragedy of Brutus the Trusting. (Blame Cassius)