On parking, it's a bit random depending on the day. On Saturday I arrived at the toll booth at 4:30PM, it was backed up a bit, and we didn't get into USF until 4:55PM with us speed walking through CityWalk. They had just opened a few additional security lines as we got there, so that helped us breeze through security, but it was quickly building up behind us. I'd say aim to be at the parking booth no later than 4:15-30PM. They do open the secondary parking plaza on HHN nights and is less busier, so recommend that if you from Hollywood Way.
However, if you want to do NY zone, I'd aim to be at the zone by 4:30PM. They are enforcing capacity limits this year.
On teens, they're annoying but not any worse than years prior. Did see a group start dancing for Tik Tok in the middle of a zone before they were quickly shut down by zone supervisors.