Hi rach,
Sorry to be answering a bit late - I got my Bumwear nappy but haven't tried it yet as our washing machine is broken (boo hoo!). So we're in disposables for a while. It looks gorgeous though, and very convenient with the one-size design of it. My baby is 12 months though, so can't comment on how it works on a newborn. I think with one-size nappies you do compromise on trimness. If you are happy to accept that it might look a bit more bulky while they are tiny, but that the payoff is that you don't have to buy more nappies as they grow bigger, then it would be a good choice.
(Edited to add, if you buy Bumwear, don't forget to add inserts to your order. They are listed a little further down the page. There's no reason you have to use the Bumwear ones, you can stuff anything absorbent inside, but if you buy theirs, you know they will fit and it's convenient to get them all at once).
It is really hard getting your head around all the bits and pieces associated with nappies, I agree! You're right in your list of things you need, but not all nappies need all the elements.
A 'pocket' nappy like Bumwear does not need a cover. It's waterproof already. What it does need is an insert, which is a piece of absorbent fabric that you put inside the nappy. This kind of nappy is great for Hong Kong, as it dries quickly (as do flat nappies).
Boosters are not essential, but they are good if you want extra absorbency, such as if you're going out, or if you want a nappy to last a bit longer. So for a pocket nappy, you'd put that inside with the insert. The good thing about that is, with all the absorbent stuff inside the nappy and not sitting on top of it, there's only the nice fleece nappy lining touching baby's bottom, and it helps keep them dry. With flat nappies and covers, the baby's skin is in contact with wet cotton.
Liners are also not essential. They just make life a bit easier. Personally I wouldn't bother with any non-flushable liners, since you still have to wash them off and put them in the nappy bucket. Flushables are very convenient - pick up most of the poo inside the liner and put it into the toilet, hopefully without getting your hands dirty! If you don't have a liner, you have to wash the solids off into the toilet before putting the nappy in the pail. It's ok, but I can imagine with a newborn it just adds that extra hassle when you have so much on your plate.
Bambino Mio flushable liners are available from Eugene baby stores and also somewhere else that I can't remember. Rani mentioned above that she got some liners from Mothercare.
MamaS, Mothercare does plastic pants too
