Fortunato, you should really get that cough checked out.
All of you, stay here until the morning.
I can't wait to get revenge!
This guy is so nice.
This is verbal irony because Montresor says something to Fortunato that implies he cares about his well being, when actually Montresor doesn't care about Fortunato at all.
Prove your a Mason.
See, I am a Freemason.
This is situational irony because Montresor knows if he tells his servants to stay at his house, they'll end up leaving and the house will be empty.
I drink to the buried around us.
This is dramatic irony because for almost the whole story Fortunato doesn't know that Montresor wants to kill him, but the reader knew Montresor wanted to kill him since the beginning of the story.
Cough cough cough*
Montresor's tries to prove to Fortunato that he is a Mason by showing he has a trowel. When he pulls out the trowel Fortunato is kinda freaked out for a little bit and took a couple steps backwards. This foreshadows that the trowel will lead to the death of Fortunato.
The narrator has Fortunato say this to forshadow that Fortunato will soon be buried.
Fortunato says he shall not be killed by a cough, foreshadowing that he will soon be killed by something or someone else.