Kim's wedding gown was fabulous! Her diamond-encrusted headpiece is very envious, too!
I don't see anything wrong with her request for guests to wear either black or white. Maybe not to outstage her, but basically, to be reminded that you are attending a formal event, not a red carpet premiere or children's birthday party. 
I am just curious with the other gowns she wore. They say she wore three gowns, but I have searched all over the internet and I can only see the same white gown she wore down the aisle. I wonder when they will release other photos.