Because Enotes only allows one question at a time, your questions have been edited to one. If you will type the others into the search box for this story, there are answers already posted which have relevance to your question and should assist you.
In reference to the question regarding Fortunato's actually being an insulting person, Poe's use of the unreliable narrator provides no certain answer since the reader only knows what Montesor relates, and he does not seem to be entirely stable. However, there are indications that Fortunato's ego is large and he prides himself on being a connossieur of wines. Because of his pride, it seems plausible that he would deprecate others; in fact, he does dismiss Luchesi as an inferior,
"....And as for Luchesi, he cannot distinguish sherry from Amontillado."
When Montresor finally leads Fortunato to the wine in the depths of the catacombs, he tells his victim, "...herein is the Amontillado. As for Luchesi--" and the proud Fortunato angrily interrupts, "He is an ignoramus." So, he does insult Luchesi, whom he considers an inferior opponent of his. Never does Fortunato insult Montresor, however, as there must be no jealousy or grudges towards the narrator. That Fortunato does not entertain any suspicions of Montresor seems to indicate that he has no antagonism toward his torturer, only towards Luchesi.
Fortunato does not seem like an insulting person, but the narrator only specifies one insult while he accuses him of a "thousand injuries." The "insult" might have been unintentional or even imaginary, but the thousand injuries need to be considered. Does Fortunato seem like a person who could commit that many injuries? If so, why would Montresor put up with their relationship long enough to allow him to do so? It would take years to commit that many injuries.
The third paragraph of Poe's story strongly suggests that Montresor and Fortunato, though aristocrats, are making money by dealing in such expensive merchandise as art works, antiques, jewelry--and presumably gourmet wines. They have their palazzi in a port city which has to be Venice. Fortunato is rich and well connected. Montresor is poor and just getting by. He may have to depend on Fortunato for loans and cooperative ventures. Fortunato could have "injured" Montresor by outbidding him and in similar ways--in fact, Fortunato is planning to buy up the whole cargo of Amontillado if he tastes it and verifies that it is the authentic Amontillado. And furthermore, Montresor knows that Fortunato is planning to do so. This would be perhaps his thousand-and-first injury, because Montresor would have bought more if he had been sure it was the right stuff. His only reason for asking Fortunato to judge it is so that he will know whether it is safe to buy more for future resale, and Fortunato's only reason for being in such great haste to sample it is that he wants to buy as much as he can for himself. He is capable of tasting the wine, shaking his head, and saying it is only ordinary sherry--then rushing off to buy the whole cargo!
The Amontillado, of course, doesn't even exist, as Fortunato will shortly discover. The trickster will have been outtricked.