My first Pit concert was the GNR concert in New Jersey last year. It was amazing and seeing them so close was unbelievable! As for your questions about the pit, based only on my experience, I was on the rail during the concert. I got to the stadium 4 hours in advance. They announced a heatwave that day which may have made it easier to get on the Rail. We got in, went to the left side (Duff's side) of the stage and propped ourselves there. My wife went to the bathroom right after we arrived and got a couple of drinks and food. She made it back to her place easily. I didn't go to the bathroom but didn't drink much of anything especially not alcohol. The people in the pit was amazing. Very friendly, which was a great group of us waiting in line together. There was a little pushing, but not much. Most of the troubles were from people arriving very later after the opening act and trying to push their way to the front. The security was very good at this concert at making sure those pusher went to the back of the pit.
My next Pit concert is coming up and I plan on arriving 6 hours in advance (depending on the weather). I don't mind waiting if I can get on the Barricade. Good luck getting tickets and you will absolutely love being in the PIT at the concert. You won't be able to get seat tickets again after this experience.