Campsite will just let you in to find your own pitches, if you struggle, find the guy on the moped with the googly eyes, he speaks good english and is really helpful. We arrived last week and were the only ones there, and within 36 hours it was full of 24hour race visitors. You'll be there in the run up to Rock-am-Ring so it'll get gradually busier, but i'd expect plenty of space to be available on arrival.
Electric is 3eu a day and well worth it, we took an event shelter, a fridge, a sound system and a strip light. it's a standard round 16amp plug in