This part of the guide will explain how to keep yourself fueled and thrashing through the festival, and help you navigate the maze of overpriced and often crappy food vendors.
Do not buy pizza in Germany. Do not buy doner at a metal festival.
The explanations for these are simple. Pizza in Germany, especially if you grew up in one of the Italian-heavy sections of the US, like I did, is simply and uniformly godawful. It is crappily made, and at Wacken, often poorly cooked. The doner are a slight improvement, but pale in comparison to the real thing from a real city donerladen. They're less likely to make you sick and will deliver more vitamins, but this is a very relative comparison, and you can pretty much put vitamins by for a week or so, can't you?
Eat the set breakfast (Fertigfruhstuck) from the breakfast tent with either OJ or coffee, depending on how messed up you still feel. This includes two nice tough rolls, butter, cheese, salami, fruit preserves, and nutella. Eat all of this, though you can save the nutella for later. This will fuel you up with immediate energy as well as real nutrition and keep you going for an hour or two until the infield opens up and you can start eating from the Schwenkgrillen.
While thrashing, you will burn energy and eventually get hungry. At that time, go get yourself a Krakauer Wurst. The Krakauer is moderately inexpensive (3 euro), and you get a foot-long, inch-thick sausage full of meat and some nice peppers that go well with the beer being served everywhere. They are one of the great reliables of Wacken, served simply on another roll, and as such they combine the complex carbs and protein that you'll need for long-duration energy release.
Also recommended are the Wiking Burger (everyone who goes to Wacken should have at least one, but they're expensive), the giant hotdog (loaded up with pickles and other veg, it's like a doner that doesn't suck as bad), and the famous Knobi-brot. This I tend not to favor because it's not quite real garlic bread. The grills where you will find the Krakauers are also the closest food to the most of the musical action and to the infield bars, making them the most efficient way of keeping your motor running whether you're rocking or drinking.
The cheapest place to get food (and alcohol) in Wacken is at the Edeka-market in town. This is a fair bit of a walk to get to, but will allow you to stock up on eats for your campsite if you consider the breakfast tent too expensive, or the beer to be a ripoff. Good options include fresh bread, which will keep more or less until Sunday morning if you buy it Thursday afternoon and eat it piecemeal in the mornings, and the ingredients for vodka-tea.
This alcoholic beverage keeps your buzz on at a discount and keeps you hydrated as well, and you'll probably be able to bring it into the infield. To make it, you will need to bring to Wacken a small funnel and to buy at the Edeka two liters of vodka and five 1.5-liter tetrapaks (most non-carbonated drinks in Germany are sold in square cartons rather than bottles) of cheap iced tea, while someone else gets or brings a standard 0.4-liter Wacken cup.
From each tetrapak, pour out 0.4 liter of tea into the Wacken cup. You can drink this if you don't want it to go to waste, or just dump it if you don't care. Now, pour out a full 0.4-liter measure of vodka into the cup and put the funnel over the opening into the first tetrapak. Pour the vodka in, close the cap, shake it up a little, and obviously repeat for the remaining four boxes.
This should take care of a significant portion of your drinking needs for the three days of the festival, if you take one pack down on Thursday and two on each of Friday and Saturday. Tetrapaks are allowed into the infield as long as they aren't of alcoholic stuff, and you've got boxes of iced tea, not booze. The security doesn't check such very carefully, and at the tincture suggested above, the paks aren't going to be exuding an obvious booze stench that will cause the secus to take notice.
Get a Mass as early as possible; this is the liter-mug, and they nearly all vanish very quickly. Out of the deal, you get a nifty souvenir mug (3 euro deposit) and the ability to significantly moderate your drinking. You'll be much more able to remember how many you've had, and when you got your last one, and the pure size of the vessel will make you pay a little more attention to how much beer you're putting down. The bands start at like noon on the two main days, and you don't want to be so totally trashed by 2 AM that you can't remember how the headliners were. It also becomes substantially braggable to the home folks who think of beer in 12-ounce increments: "THIS is how we drink in Germany!"
Expect to spend about 40 euro on beer per day, and another 20 to 30 on food. This assumes that you are not being parsimonious, but eating and drinking like a Viking on his king's tab, which is overwhelmingly the case at Wacken. This makes about 180 euro in food and booze expenses (splitting the difference, and since Thursday is a short day), before we even get into merch. Plan accordingly! Don't be that guy running around on Saturday night with a sign begging for money to help with alcohol research or food!
With this in mind, you can moderate this by buying breakfast stuff from the market instead of the breakfast tent, and you can shave about 20% off your beer bill by using the vodka-tea recipe given above.