Hey Rudi,
So jealous mate, would love to be heading back this year but it will have to wait. The Simms wet wading socks are the real deal and I highly recommend them. I ended up with a couple of extra pairs from my trip last year so you are welcome to borrow if you like. I also have a Simms sling pack in a large that your welcome to. I would go a sling any day over a bum bag or back pack. Comfortable and practical... One thing to keep in mind though is that you may want something fully waterproof if your walking with expensive camera gear.. Deep wading (although infrequent) and rain squalls are your main traps, particularly if you day walk into Y-site (in my opinion a christmas island must). As for the boots, think hard about this one and don't compromise. The Mirage tungsten studded booties is your cheapest way out (although I remember u saying that u were not impressed with them). Next up the simms flats sneaker for sure. I read several negative reviews about these, however those whom used them from our group had no issues over a 2 week trip.
I'll let you have a raid of whats left of my flies and if you want to fix me up a few bucks then great.. One suggestion I have though is don't go too over the top.. The range of colours and weights can be really confronting and on a whole we found that colour didn't matter that much, although on that I would say that a pink body with a pink crystal flash tail and underwing, completed by a Tan over-wing was the colour most preferred by our guides (The Villages). Definitely keep a few in handy in bright orange as these also work great for trigger fish.
Will stop there before I turn this into an essay, lets have a rave sometime soon over a beer
All the best,
Dan