Hi,
We went last year and had a blast,
Definetly get a trolley, for setting up camp and round the festival. There's a few activitys on the lake and wild swimming so we used the trolley for transporting wet kit/changes of clothes/dry robes/camping chairs, food ect.
Trolley meant alot less going back and forth to the tent everytime we got wet.
It can get busy and you will need to queue for certain activitys, so best to do your must do activitys on the first day. There's no day tickets sold for the first day, its campers only so it's much, much quieter than the rest of the weekend.
Site was well lit, security keeping an eye and felt very safe. Not at all muddy when we were there, but we got lucky with the weather and it was sunshine for the entire time apart from 20 minutes of drizzle.
I would pack waterproof everything and wellies just in case, as the paths to and from the campsite are dirt paths so probably very muddy if it's wet.
Can't comment on the showers as we brought a camp shower but our friends used them and said they were decent.
Loos are all portaloos but clean and lots of them.
There's no food shop/camping essentials shop on site, so if you need more gas, pasta ect you need to go off site.
Most of the activitys you need trainers for, not allowed to do them in sandals.
It is very tiring! We were doing activitys from about 8am - 6pm and then dancing to the bands until 11pm, so it's long days!
Hope that helps :)