Cocos is great for kiting and you can do your own thing with downwinders, most of the accommodation places have bikes so just leave a bike down at the old wharf to ride back home on. Do a down winder in the morning and stop off for a surf on your ride back to town, hook up with a local and they usual offer you a board to use from the shack
For $20 dollars you can join the yacht club (large shed) and you can store your gear in there. It has its own BBQ area, toilet and fresh water.
There is a sign on the side of the runway with the Airfield Operations Manager Mob No, give him a call and he will let you know what days there are no flights and when its ok to do a downwinder past the runway.
On the down side food is very limited and expensive, there is really only 1 supermarket, 1 cafe and one other eatting venue. As an example breakfast out would be around $35pp. You can pick up fresh fish from one of the boys at the club for like $10 a kilo which was amazing on the BBQ.