Re. showers - have a look at the solar shower bags, about £8-10 on Amazon, fill up at the taps - leave out in the sunshine (which there will be plenty of again for next year's Glasto..) and you've got a hot shower ready to go
If that is correct then I imagine it will be Justice or Basement Jaxx to close. Be great to see that format feature regularly again as it was pretty common when I started going. Had some great finishes to the night on the Main with the likes of Kraftwerk, 2manydjs, Deadmau5, Chase and Status and Basement Jaxx, who were actually on the very first year I went.
Had it on good authority they tried to book Chappel Roan last year so would make sense if she's playing next summer.