"We will go back; you will be ill, and i cannot be responsible. Besides, there is Luchesi-"
Montresor was actually meaning the complete opposite, and trying to compete Luchesi with Fortunato. But Fortunato said he can do it because he wanted to taste the rare wine.
An example of foreshadowing is when Montressor explains his family motto to Fortunato, which is "No one attacks me with impunity." Fortunato responds with "Good." Fortunato had know idea that Montressor was going to leave him in the catacombs.
Fortunato exclaimed "let us be gone." Montressor replied "Yes"... "Let use be gone." Montresor instead left Fotunato tied up and left him.
Motresors family picture is a symbolism of someone attacks me I will attack back
Motressro told his help to stay home, but he was not going to be home. So he would not know if they went out or not. He used reverse psychology, because if he wasn't going to be home, his help could leave.
Poe set a tone of a dark and eire. Also the way he narrates and describes his actions makes it intimidating.