speaking as the out of country person who attended last year and the year prior but with last year being a mudshow.. make sure you bring a couple jackets (mine was soaked standing in line to get in last year which left me having to buy a new jacket), bring running shoes that you don't care about them ever being the same again (not white either), also bring a sweater (which I forgot as well) and lots of dry socks.. lol.
(this is if it rains of course)
I am not much of a camper though so for me it wasn't always very pleasant. Ask Phor how much of a happy camper I was standing in the rain, waiting to get in and soaked from head to toe. I was ready to go home at that time. Once you get in though and get to a tent with some good tunes you will be set to go (if it does rain). And as far as drinks, we were allowed 3L of water last year, but nothing alcoholic and for food, well that was the last thing on my mind so I don't quite remember. Although I think Jasper and I got in some cinnamon buns or something like that.
And last but not least.. make sure you check the weather before going cuz you never know if you may have a surprise for the Saturday and you will want to be prepared. You will be in Holland afterall, so you will want to be prepared just "in case"
Have I missed any key items guys??