The big secret-secret was really not that big of a deal. =) After completing the first version of this dress, I thought that the side front, side back, and back panels looked a little wide. So, I made extra seams by splitting each of these panels into two pieces.
The topstitching along each seam follows the curve of the dress nicely.
I found a fix for my facing problem. In this post, I mentioned how I neglected to cut out the facings. By the time I realized it, I didn't have enough fabric to cut the facings in full length. I managed to squeak out just enough to catch the roll of the collar.
Next, I added length using a double piece of cotton broadcloth from the stash. A single ply of broadcloth wasn't heavy enough and would have made the front of the dress drape differently. Even though two plies isn't quite the same weight as the denim, it is heavy enough to provide necessary structure and from the front, you can't really tell the difference.
I used A LOT of steam, heat, and a couple of pounds from the clapper to make sure the seam joining the top and the bottom was perfectly flat.