Unfortunately, you are not allowed to ask more than one question, so I have chosen to focus on the theme of this terrifying short story. From the very first paragraph it is clear that revenge is Montresor's central motive for acting in the way that he does:
The thousand injuries of Fortunato I had borne as best I could; but when he ventured upon insult, I vowed revenge.
Although the exact nature of this "insult" is never divulged, revenge is the driving force that leads Montresor to plot and enact his most gruesome of punishments. Consider Montresor's motto, "Nemo me impune lacessit", which means "Nobody attacks me without punishment", which adds a moment of black humour to the story as Fortunato responds to the firmness of this motto with a strong approbation: '"Good!" he said.' Of course, the first paragraph is key to the reader in terms of displaying Montresor's plan, which is an enactment of his motto:
A wrong is unredressed when retribution overtakes its redresser. It is equally unredressed when the avenger fails to make himself felt as such to him who has done the wrong.
It is vital therefore to Montresor that Fortunato meets his fate at his hand - Fortunato must know that it is Montresor who is exacting the revenge himself, otherwise, by Montresor's definition, it would not be revenge.
Thus it is revenge that drives Montresor and impels him to devise such a terrible manner of achieving his revenge against Fortunato, which, of course, allows Montresor to observe first hand the revenge he is gaining against his enemy, bricking him in to the depths of his catacombs as he locks away his crime in his mind and re-enters the light of day again.
what is the theme of the open window?