I think I can answer some of your questions - a few were answered on this thread. I had pretty much the same questions! It’s seems like if you have a conflicting reservation, it is up to you to change it. I know I’ve heard they are pretty accommodating since they want you to enjoy (purchase) both. The night we are in port, I’m going to quickly make my excursion/other specialty reservation decisions as soon as I find out our reservation time for the Dinner on the Edge/Magic Carpet.
As for the meal, I’d assume there aren’t up charges (usually it would be listed on the menu and I don’t see any.) and from the sounds of it, you get to try everything listed!! I’d also guess whatever wine package you already have would kick in. ((Again, since not on the menu - which was great to have a picture of here. Really looks delicious!)
Hope that helps some!!