Calpurnia's cot shows how segregation is everywhere in Maycomb, including the Finch home.
We know that Aunt Alexandra has somewhere to sleep when she stays with them, suggesting that they have a spare bedroom. However, when Calpurnia stays with the Finches, she is not allowed to stay in the spare room.
Im sorry, is there supposed to be a picture
This means that he feels very drugged as if he had just taken an opioid or something. He hears a nightingale singing saying that the bird is spreading its happiness too much. He is also saying that he too is happy because he can hear the nightingale sing somewhere amidst the forest.
She's able to be happy at some points. "Turning on the light upstairs" is a way to "turn on" happiness.