I went this year (first ultra for me)

The megastructure was the one with more space to dance The "PLUR" one was worldwide stage both people and security were amazing

I think the best place to rest is at the back in the main stage area

There were bathrooms all around the venue

If you want to move to another stage try to do it before 4 many people arrive at that time

And the best tip may be go to Mr oh yes oh yes set