What's Up with the Prelude to Act 3 of Lohengrin?

Can anyone tell me what the Prelude to Act 3 has to do with Lohengrin? It sounds like a twisted mash-up of the Roman Carnival Overture, the William Tell Overture, and the Ride of the Valkyries, that accidentally wandered in from the opera playing next door. 

The first and second act preludes reflect pretty much what is going to happen. The first act prelude sets a misty, mysterious tone (which, of course, is hijacked temporarily by the Heerufer and the Männer von Brabant) of Elsa and Lohengrin’s set pieces in that act. The prelude to Act 2 contains Ortrud and Telramund themes and leads us into their scheming to get back at Elsa and get rid of Lohengrin.

Does anyone else think Lohengrin should have just killed Telramund when he had the chance? Of course that really would be a different opera. The opera where Elsa says, “Sure, I trust you,” and doesn’t ask his name, and they live happily ever after. That also could lead to the sequel called Gottfried when he comes back to lead Brabant, and then there is friction between the brothers-in-law; or tragedy ensues when Lohengrin has to leave Elsa and this time she really dies; or we can go Ring-style, and Gottfried and Elsa could get married and have a son named Gottmund. But I digress.

Then, between the procession to the Minster* that ends Act 2 and the Bridal chorus that begins Act 3, there is this big, loud invasion of Valkyries, Roman carnivals, charging horses, and who-knows-what-else. On the “Rat” Lohengrin DVD they showed one of the strange rat animations—in the web version they showed a cool time lapse of the stage crew setting up—that reflected the energy of the music, but still didn't make much musical sense in the opera. So, is this music the wedding ceremony? Or the big party after the wedding? But don’t they pretty much leave the Minster and go straight to bed? It's not them in bed, because (we think) they never make it there...

So, what is that prelude doing there? I welcome any and all suggestions. (And/or discussions of further Gottfried operas. Maybe when he comes back, he marries Ortrud...)

*That reminds me, I forgot to complain about that poor excuse for an organ they have at the Met. That was pretty disappointing in the ’86 Lohengrin video.