Melinda says the number 2804 next to Andrea's name is because she died on April 28th. In the season 2 finale they said the plane crash, in which Andrea died, happened on May 11th.
The wedding planner says "half a dozen", then corrects himself by saying "6 to be exact".
Except half a dozen is exactly 6. A dozen is 12, there's no leeway on what half of 12 is.