He had a weak point --this Fortunato --although in other regards he was a man to be respected and even feared. He prided himself on his connoisseurship in wine. Few Italians have the true virtuoso spirit. For the most part their enthusiasm is adopted to suit the time and opportunity, to practise imposture upon the British and Austrian millionaires. In painting and gemmary, Fortunato, like his countrymen, was a quack, but in the matter of old wines he was sincere. In this respect I did not differ from him materially; --I was skilful in the Italian vintages myself, and bought largely whenever I could.It was about dusk, one evening during the supreme madness of the carnival season, that I encountered my friend. He accosted me with excessive warmth, for he had been drinking much. The man wore motley. He had on a tight-fitting parti-striped dress, and his head was surmounted by the conical cap and bells. I was so pleased to see him that I thought I should never have done wringing his hand.

I said to him --"My dear Fortunato, you are luckily met. How remarkably well you are looking to-day. But I have received a pipe of what passes for Amontillado, and I have my doubts."

9. what does the narrator have in common with fortunato?
the narrator is also skillful in the Italian vintage.

10. how does the narrator appeal to his shared interest in order to secure Fortunato's cooperation on the carnival night?
idk is it that He tells Fortunato about the Amontillado

11. what costume is Fortunato wearing
a jesters costume

12. considering what occurs in the story, why does the author choose this costume? explain the irony revealed by this choice.

idk why he chooses it,

http://www.sparknotes.com/lit/poestories/section11.rhtml

11 is correct.

9 and 10 need more detail.

12 = ?

i don't know the answer for number 12

Do you understand what irony is?

http://www.enotes.com/homework-help/when-dramatic-irony-shown-cask-amontillado-3558

yes i understand but i don't know why he chose a jester as the costume. and in order to answer the irony part i need to know why?

is it becuase the jester is the one who always tells jokes makes people laugh, etc well in the end the only who would laugh would be the narrator since he got rid of him

You're getting close, yes.

The jester is supposed to make people laugh ... but this guy in the jester costume is going to kill someone, which is definitely not funny.

no Fortunado is wearing the jesters costume

but the one who wants to kill him is the narrator so how is "but this guy in the jester costume is going to kill someone" have to do with it? since its not him

Oh, sorry ... I always picture Montresor in the jester's costume.

Best read up on what a jester's job is, then ... the answer has to be in there.
http://en.wikipedia.org/wiki/Jester

Who at the party would question where a jester would go or how he would act or even if he disappeared?

its ok,

no one would question where he would go.

since they are like "clowns" you know, so they probably thought they were clowning around or something

so ester is the one who always tells jokes makes people laugh, etc well in the end the only who would laugh would be the narrator since he got rid of him is not the answer?