Jut got home from my Pandora Preview a few minutes ago. WOW!!! That layers upon layers of detail just cannot be described.
I have no idea if this will hold out for others but on the 6-8P preview this afternoon, they started scanning credentials (bands or cards) a couple minutes after 5PM. Right after they scanned our credentials a CM came by with a stack of paper FP's with 15 minute windows for FoP. Due to problems continuing with FoP right now they did not give out enough FP's for everyone to get one. Some further back in the line got a voucher for a free drink at Satuli as consolation. So if this model plays out going forward you'll want to be there 90-120 minutes before your scheduled preview window to be toward the front of the line. I'm sure as FoP gets more reliable that will change but this is what we experienced earlier today. There will be a pretty epic line just waiting to get into the land.
You do not need any paper or emails or anything else. As long as you can see the Rivers FP in your MDE, all you need is your MB or card which they'll scan with the hand-held scanner and you're good to go.
They let us stay in the land until a little after 8:30P when they began a very aggressive sweep to run everyone off. That meant we had 3 full hours in the land when it was all said and done. Despite the darkening skies they did not turn on any bioluminescence or lighting on the floating mountains. Some of what's on the paths was visible as the lights that drive those came on for basic safe walking. We were told that the full lighting package will not be turned on until the media preview and the official opening on the 27th and then it will be on for everyone going forward.