what is the metaphor in "My pencil is...My ally on my test, Always sharp helping me every day." and what is it comparing?

Acomplex sentence contains . one subject and one verb

Read the excerpt from "the love song of j. alfred prufrock." and indeed there will be time to wonder, “do i dare? ” and, “do i dare? ” time to turn back and descend the stair, with a bald spot in the middle of my hair— [they will say: “how his hair is growing thin! ”] my morning coat, my collar mounting firmly to the chin, my necktie rich and modest, but asserted by a simple pin— [they will say: “but how his arms and legs are thin! ”] do i dare disturb the universe? in a minute there is time for decisions and revisions which a minute will reverse. which lines indicate that the speaker is concerned about what others think of him?

Wiesel interrupts the narration that begin with, "a few ss officers wandered through the room, " with a parenthetical insertion. explain the purpose of the insertion.