To take one bit at a time:
Customs: If the Douanier isn't behind his window then make sure you book in with the aerodrome authority (who'll take your landing fee and arrange fuel for you). Normally no hassle though
ATC: Ok until it gets very busy, then it becomes a bit of a lottery. You'll discover that aviation french is more long winded (the regulation is that French aircraft are controlled in French in France) so you'll get hacked off when you're trying to get a call in and someone's jabbering away. C'est la vie as the locals say
Most of the rest - look at
Le Touquet website
Aircraft Parking - in front of the main terminal - loads of space
Camping next to - no chance, it's all tarmac
It's an easy intro to going foreign - enjoy