Baz - d-d photographics is not an official Australia distributor. No official warranty. I'd buy from an Australian based retailer. I can recommend Quality Camera (based in WA). Their page on the 5D Mark II:
http://www.qualitycamera.com.au/cano...ra-p-4337.html
priced at AU $3999 body only it seems. DD is only $300 cheaper, not worth it imho. Note Quality Camera's page on parallel imports:
http://www.qualitycamera.com.au/note...as-p-4314.html
you have been warned!
Canon lenses can be bought anywhere around the world - they have a global warranty, unlike the bodies.
I'd also recommend the 16-35 f2.8 L series wide angle zoom, some have expressed concerns with the optical quality, a review for your enjoyment:
http://www.photozone.de/canon_eos_ff...non_1635_28_5d
Tripod - either a manfrotto or gitzo if you want to lash out. It's a personal choice thing. My personal take is to visit the local camera store and play with the real McCoy and see what you like, and what is comfortable to use/carry, and also, most importantly, sturdy.
Flash - you could go a 430ex or the 580ex II - I'd go the latter. It can wirelessly control another flash for starters (Canon one of course), is very powerful and has weather sealing on the base. I'd still avoid downpours though!
Intervalometer - I know nothing about this sort of thing, so can't say much.
Battery pack - imho - get it. Offers stability to the body, a bit more weight, making the camera feel more robust and makes vertical shooting easier imho. Plus, you can put a few batteries in it - 2 batteries better than one when you're out in the field!
I'd go with the Canon 100mm IS L. L series. Weather sealing, IS might come in handy (I'm a bit dubious on this aspect myself, although I've heard people enthused about Nikon's VR on their 60mm macro unit). It's a good solid length, offering good working distance, and is not too heavy or large. The weather sealing is handy. Macro imaging is nature photography, and, imho, weather sealing is a must when you are out in the field.
For macro, I'd also recommend a set of Kenko tubes, and the Canon offshoe adaptor (#3 from memory). The Lumiquest diffuser that Troy reckons is very good by all accounts, although I haven't personally used it. I am thinking of getting one though lol!
Troy's comment on a lens between the 16-35 and 100 macro is a very good one - I'd recommend one of Sigma's 24-70 f2.8 units. Cheaper than Canon's and just as good as optically imho. For a longer lens, save the biccies for later on and get a Canon 400mm f5.6 L (birding, general natural/wildlife/portraiture shots). As always, I recommend the "nifty fifty" (Canon 50mm f1.8 II). Cheap, but very good optically imho.
As an aside, there's no reason why your 400D *can't* do good macro. LordV (the best macro imager in the world imho) used a 350D and 20D for a long while. He is now using a 5D Mark II and has privately reported to me that the IQ is very nice.
One other thing (and AlexN and Troy will hate me lol!!!) - have you considered a Nikon D700? You haven't invested much in Canon, and you might want to consider alternatives before you get financially committed to Canon. If it was me, it'd be a D700, no brainer imho. The 5D Mark II is very nice, good IQ, but I don't need, or want that many megapixels. 12mp is perfectly fine imho, and I'd rather have those larger pixels, better noise @ high ISO, and a far better dynamic range. I'm personally not impressed with Canon's high ISO performance (at least when compared to the competition). From a personal point of experience, Canon Australia's support has been atrocious to say the least - at least to me.
As I said to a girl @ work today - I'm currently tipping up whether to go with a Mark IV or sell my Canon gear and move to a D3s. I'd lose a fair bit financially, but the lure of what I consider better quality of the Nikon units at high ISO is really appealing to me.
Dave