Hey Chris.
I spent 2 weeks over there in august. Had a ball.
In a nut shell. Camping areas are good, with toilets. There are a lot of birds in the island. They make noise all night, and will shit on everything. You will want tarps over everything.
A 5m boat should be fine on the barge.
The lagoon is dry at low tide, some access in and out in the boat is 2-3 hours either side of the high tide.
There is good fishing a few kms from the island, to as far as you want to motor too.
i went with a big group (23 blokes), so we had lots of gear, but the numbers of blokes made for the work to be shared, but carrying everything up and down the sand get really old very quickly, so make sure you don't take unnecessary gear.
How many are you looking to go with?
Hit me up with any questions you have mate.
Cheers Rob