I got impatient waiting for the Disney Blog to update so I called the park and talked to a really really nice CM who even put me on hold for several minutes while she tried to find information for me regarding the deal with the merch line.
So if this is in conflict with what they post on the blog, hopefully soon, then do with this what you will.
The Merchandise line will enter on the left side entrance. The regular park line will enter on the right. I wasn't able to find out where the early line up area was, but I would assume they will be right next to each other where we have heard it may be already. Anyway, when the park opens, this merchandise line will be directed to the Animation Building. They will allow groups to go in (not sure how many in a group, depends on room capacity size, not too huge) and these groups will be allowed a certain amount of time to shop and purchase. They will be directed to leave and the next group of shoppers will enter. At that point you are free to go about the park as you wish.
I don't have more info on how it will work with the wristbands. I don't see how it would be any different than the park line. But we shall see. Hopefully the blog will give us more info.