1. There is tapwater, you can bring your own bottle
2. There is body search, but they aren't allowed to search your bags, they can only look in it.
3. It hink it is allowed.
4. A drink/food ticket is €3, a drink is one ticket, cocktails 3 tickets, food is between 1 and 4 tickets. You can buy tickets cheaper in presale. There is food in the street outside the festival site that is provided by neighbours and is cheaper.
5. I've been in Camping Relax once, and it is, not suprisingly, relaxed. Not much of a party at night, almost no queues.
6. I advice you to take the free shuttle to the festival site. You can walk, but it is far. Shuttles ride every 15 minutes, more or less.
7. I don't think this is an option. The lockers are in the festival area, after the check by security. I don't think a big backpack is allowed in the area. The XL lockers aren't that big.