Quote 10
I had finished a portion of the last and the eleventh; there remained but a single stone to be fitted and plastered in. (80)
The revenge is almost complete. After Montresor puts in the last brick, Fortunato will be in no position to re-revenge himself on Montresor. The brick wall also suggests the bricked up psychology of both characters. As long as that small opening remains, both characters have a chance to be free of the cycle of betrayal.
Quote 11
For the half of a century no mortal has disturbed them. (91)
The big reveal at the end: Montresor’s revenge was successful, and he’s gone undiscovered for fifty years. Also note that it doesn’t say the bones outside of Fortunato’s crypt haven’t been disturbed at all, just that they haven’t been disturbed by ‘mortal[s]” − surely ghosts and ghouls aren’t out of the question.
Quote 12
[…] 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 […]. (5)
Does this just mean that they are both a bunch of drunks? Montresor’s statement about Fortunato does seem to prove true. Fortunato is sure sincere about trying to get his hands on some Amontillado. So sincere it costs him his life.