Hi Iain
It's not that complicated, a google search will reveal all the accommodation options, there aren't that many. You do need to consider booking many months in advance especially if you're looking for the cheapest options. You do pay a lot for really basic ''3 star'' accommodation but that's what it is...Food is easily 2x more expensive than in Perth and your options are limited. You are however allowed to bring an esky full of any food you want on the plane, provided it comes from WA. On the plus side liquor is very cheap (duty free) but beer isn't as it's more expensive to deliver.
You need to consider hiring a car or moped to get you from your accom to the kite beach, which is only about 5KM but too far to walk with gear.
www.windfinder.com/windstatistics/cocos_keeling_islandAs you can see, the very best months are July through to September.
There is never a guarantee wind wise. I've seen people come for 5 days and not have anything more than 15 knots, which can be very frustrating. I was there for about a month in 2014 and was lucky to have many days of 25 knots + Essentially you have to expect just about anything really. I was told to bring a 17m kite but NEVER used it once and really wish I brought my 7m instead.
I personally found the winds to always be gusty i.e. at least 5 knots variation in the lighter winds and easily 10 knots variation in the strong winds. Those gusts make it not as enjoyable as the seabreezes we have in WA, however you can't complain that much cause you're in an warm tropical paradise with a steady 28 degrees day and night.
You also can't kite at low tide at the main kite beach simply because the water is too shallow. You also have to be very careful if you don't wear booties to not cut your feet on the coral. It happens often and a simple cut can ruin your holiday (no more kiting)
There is great surf if you happen to be a surfer but no real safe spot for kitesurfing waves. So essentially it's only a good spot for twin tips.
Hope this helps
Christian