Many of your questions are "TBD". Parking structures usually open one hour prior to park opening. However, I imagine this will change with Potter-phobia.
"Rope Drop" usually happens within the main entrance leading up to the first Digital Directory board. There is now an audio announcement welcoming the guests and a "Lights, Camera, Action!" moment. Not often is this done early unless its been an extremely crowded weekend.
Since FOL does not work in Orlando, it will be tough to gauge this for Potter. I can imagine we may follow a similar structure to Japan, but that is just a guess. FJ is plagued with long lines and a slow load. I can imagine VIP may get access, but standard FOL may be a tough sell.