Swann&Sparrow: If I could choose two people to be together, it would be Norrington and Elizabeth. I think they are excellently suited to each other personality-wise, they look good together, and they are both incredibly smart.
As for who I believe is going to end up together, it's W/E. I see no way that Elizabeth and Jack would ever be anything more than a "What might have been" couple.
Also, in the visual guide, it mentions that Beckett waited for the right moment for when to come to Port Royal...that moment was the wedding of Elizabeth and Will.
And yes, Beckett would have known about the wedding...That kind of news would have been considerably exciting, since Will and Elizabeth is a forbidden love The lady marries a man below her station? Unthinkable! The circumstances surrounding the engagement would have been shocking too, what with pirates and a broken engagement to a handsome Naval officer...the rumors probably spread well beyond Jamaica and the colonies.
After all, if Beckett knew about the compass, the chest of Davy Jones and Jack's escape, why wouldn't he know the date of Will and Elizabeth's wedding? It's not like today, where you mail an invitation out and people get it in a week or less; back then, it took a looooong time for news to travel, so there was plenty of time for Beckett to hear about the engagement.
Everything Beckett said in the movie was done to manipulate others, from mention Norrington and Sparrow without their titles (I believe he was testing the waters to see which person the others cared about more), to his non-surprise at Elizabeth getting the letters to getting Swann to work for him, Beckett had planned and mapped out all of their movements and responses. He'd be one heck of a chess player, I bet.
So no, it wasn't fate. Beckett doesn't believe in fate, he believes in himself. He's pretty much telling her that he is in control, that he'll do what he wants...when he wants. Beckett never says anything without purpose, so no, it wasn't a random comment from no-where.
To make sure I cover all interaction between Beckett, Elizabeth and Will, I might as well add that when Beckett off-handedly points out how much trouble she's going to for Sparrow, and she protests, I think he is simply fishing for information on how much she cares about Jack.
I think up until the point where Jack was so flippant about Elizabeth's plight when they got onto the Pearl was where Will decided that he'd had enough of Jack and no longer trusted him. The very fact that Jack would not hand over the compass to save Elizabeth was probably an affront to Will, and he was willing to do anything to get that key to save her, because without the key Jack would not give him the compass.
And I agree with willofthewisp; Will and Jack used each other in the first movie, and they did have a friendship of sorts. Will realized his mistake the moment he tried to defend Jack's title, which is why he's more cautious in his meeting with Beckett. It has nothing to do with jealousy, and everything to do with staying alive.