Poe needed something to lure Fortunato underground where Montresor could chain him to the rock wall and leave him to die. Wine was the best lure because Fortunato loved wine and was already drunk when Montresor found him in the street. But what kind of wine? It obviously couldn't be Italian wine because there was an abundance of that at all times, and especially during the "supreme madness" of the carnival. Montresor couldn't say that it was French wine because he was French himself and was a connoisseur of wine. He twice offers Fortunato French wines when they are down in the catacombs: Medoc and De Grave. The only other alternative was a Spanish wine. The Spanish export a lot of sherry, and the finest sherry is Amontillado. Poe may have known very little about Amontillado sherry, but he only needed to know a little for story purposes. The Amontillado, of course, never really existed.
Amontillado is a pale dry sherry made in Montilla, a town in southern Spain.
Montresor (narrator) mentions Luchesi (an expert on wine) in the hope of luring Fortunado to his vaults to try his Amontillado; it works because Fortunado considers himself to be more of a connoisseur of wine than Luchesi. Therefore, pride turns out to Fortunado's fatal flaw.
Yes, amontillado is a wine. It is a kind of sherry.
Luchesi is a person, one who is supposed to be knowledgeable about wine.
Amontillado is a type of Spanish sherry wine. It is a very nice quality wine. Luchesi is another character in the story but he never shows up. He is just mentioned to tease Fortunato.
Montrssor is saying he'll go to Luchesi to check the amontillado if Fortunato won't go. This infuriates Fortunato because he thinks he is the best at wines.
Luchesi is the man who Montresor claims he has purchased the Amontillado from. This is the lure to get Fortunato down to the cellar. Fortunato considers Luchesi to be stupid and states, "Luchesi cannot tell Amontillado from Sherry." This statement proves his ignorance as Amontillado is a dry Sherry from Montillado, Spain.
(Contributor apierce seems to have Luchesi & Fortunato confused.)