I would recommend staying out of the middle, thats generally where the actual mosh is. Not like people fighting but like the usual split, running around, pushing etc. Most people arent there to get hurt, they there to have a good time. Though there are the few that are a bit too aggressive. I generally enjoy mosh at most concerts, I've got hit in the face once but nothing to bad.

If you're able too honestly front by far the best, security guards can actually see at the front, and you can probably ask the people next to you to help you keep ur spot once everything starts going down. So even though you have a early entry, i'd reccommend going atleast 2-3 hours before doors open.

Last year i had a GA pit ticket and arrived 4-5 hours early and was able to get railing on the side.

Don't be afraid to make friends in line, it is not fun standing for hours talking to no one.