^ To answer your questions:
- Yes, there is a HUGE benefit, you can get a ride or two in so you don't have to ride any later that night and start lining up for mazes. Most will open up at 6 or even earlier but it's best to line up for them early.
- The Backlot is not open until 6:30 I believe, (pay attention when you get to the main gate before early entry, they will announce what time what opens for early entry) nor Terror Tram until 6:45, however if you start off at the Lower Lot you will most likely remain there for the rest of early entry as they tend to not let guests back up until 7:00.
If you need a plan, this is what I always recommend: The Walking Dead -> Insidious -> This is the End -> Crimson Peak -> AvP -> Terror Tram -> Jabbawockeez (if you're into it) -> Halloween. If you have time kick back at some scare zone. I hope this helps!