As the others said, if you want a good space at the front be there early and that means early am. When we went to the OWN 2001 tour we got there before just before 8am qued all day and were in front of Richie on the front row every time.
You cant take bottles in, as they take lids off the bottles(for safety reasons). Food is fine you can take anything in.
As long as its not a camera with an attachment you'll be fine.
Getting back to your space, lmao everyone moves forward as soon as someone moves but you can get there eventually. I'd suggest do everything before you go in to see the show, everyone sat down once we were in the Superbowl at MK so we went for a walk it was pretty easy getting back to where we were.