Mutton Lettuce and Tomato Sandwich

I was slicing a tomato the other day for a sandwich, and was reminded that “true love is the greatest thing in the world, except a nice MLT --- mutton, lettuce, and tomato sandwich, when the mutton is nice and lean, and the tomato is ripe.” As I pondered the truthfulness of this sentiment, I was suddenly struck with a horrible doubt about the basic stability of the plot in The Princess Bride. You see, up until the point where Westley says that true love is what he has in this world that is worth living for, I'm not sure that Inigo could have known or even had an inkling about his connection to Buttercup. Yet, when Fezzik and Inigo hear the scream while looking for The Man in Black, Inigo instantly concludes that it must have come from him.

Inigo: “Do you hear that Fezzik? That is the sound of ultimate suffering. My heart made that sound when the six-fingered man killed my father. The Man in Black makes it now.”

Fezzik: “How do you know?”

Inigo: “His true love is marrying another tomorrow, so who else has cause for Ultimate Suffering?”

Previous to this, Inigo was a drunkard (and probably can't remember much) while Fezzik was unemployed in Greenland. How either of them could know of the relationship between Buttercup and Westley is beyond me. It is possible that in a moment of clarity Inigo reasoned that Westley would only have chased them if he loved Buttercup, but it seems to me that kidnap and ransom would be a more obvious motive for a pirate. Of course, Inigo somehow also knows that Vizzini is dead, so maybe he has a gift for clairvoyance. I always imagined that this discrepancy could be easily explained by Fezzik coming upon Vizzini's dead body after sleeping well and dreaming of large women, but knowledge of Westley and Buttercup's true love would be a bit more difficult to come upon.

Perhaps some Princess Bridge scholar can straighten this out for me? Until then, I'll look for some mutton and lettuce so that I can settle my first question once and for all.