As far as Elizabeth's interest in Will -- it's a pretty small town, and Will and Elizabeth must have encountered one another fairly frequently if they have an on-going "Call me Miss Swann" thing going. I think the pirate medallion might have created Elizabeth's initial interest in Will, and obviously he's grown up pretty well too, but I think she must know something of who he is as well -- even her maid observes that Will is a fine man.