Mood is the atmosphere or feeling of a literary work, usually created by the setting. The piles of bones, Fortunato's cough and the darkness of the catacombs leads to an eerie and anxious mood, and a feeling like something terrible is going to happen.
Conflicts are struggles between opposing forces that drive stories forward. Man vs. Man conflicts are conflicts that cause people to fight other people. The Man vs. Man conflict in this story is between Montresor and Fortunato. This conflict is focused on while Montesor builds the wall that he traps Fortunato in.
Characterization is the method trough which the author develops the character. Fortunato is developed through indirect charactization. He embraces Montresor warmly when they meet in the beginning of the story. This shows that he is trusting and happy, without the author directly stating it.