What type are best for newborns? Should I just use prefolds? Until what age?
For newborns I think fitteds with covers are best. Fitteds or flats (prefolds, terries) are better for containment as they have two layers around the legs and are generally more absorbent, but I prefer fitteds over flats as you don't need to fold them. That makes them slightly less adjustable but as you have a cover as well, you still have two chances to get the fit perfect so it's usually good enough. Many people do use one-part nappies (AIOs, AI2s, pockets etc) on newborns and manage fine, but I'd say they are less likely to be 100% successful. I do think it's worth getting mostly fitteds (or flats) plus a few other types to try/play with/use for showing off/babysitters etc.
When would I use these different types of nappies? Pockets, all in ones or all in twos? Which is better or do you prefer?
One parters would generally be used during the day. Fitteds would be better overnight for reasons above. I suppose really, you might want it the other way round - one parters when you're fumbling in the dark - but I think reliability is the most important factor overnight because wet sheets are not fun.
We used more newborn sized one-parters in the first couple of days when LO wasn't weeing huge amounts and poos were small and sticky (so stayed in a coin sized splat in the middle of the nappy). After that, I kept them for when LO needed a clean nappy for just an hour (e.g. an hour before bath time) and I had a couple in the changing bag in case I ran out of clean fitteds when out.
When LO is big enough to move to the next size or one size nappies, you're far more likely to be successful with one-parters during the day as they're bigger so can hold a lot more. We've always used fitteds overnight and for naps when possible, as well as in the car.
What type of nappies need a cover? And why?
If you want them to be waterproof, fitted nappies and flat nappies like prefolds need a cover. You can use them without but the wee will soak through to the outside of the nappy fairly quickly. That's okay in the garden but probably not ideal on granny's best sofa!
I'm planning on trying a few different brands, but what are your favourites/most reliable? I hope to hear from Aussie mums too!
You are lucky in Aus, you have some great nappy makers over there! I love Baby BeeHinds - their night nappies are great for babies who wee a lot overnight. Their day fitteds are good all-rounders and their Petite AI2s are amazingly slim yet absorbent nappies. I like Designer Bums Night Nappies too (huge but perfect for heavy wetters). Itti are always popular as well - I love the Bitti Boo although I don't think it's a real night nappy (more for daytime naps). Baby Chilli makes beautiful nappies that worked really well on my LO. You have Bambooty too - another great brand.
Other brands I like a lot are Blueberry (some nappies may be called Swaddlebees but they're changing to Blueberry), bumGenius, Thirsties, Babykicks, Bummis, Sloomb, Close, Little Lamb, GroVia... I could go on all day
What do you use to wash yours? Some brands say 1/2 normal detergent, some people use dish washing liquid etc. it's confusing. Is there one product i can use for all brands?
There are no hard and fast rules for washing nappies and anybody who tells you otherwise doesn't understand the many different factors at play. Your machine, your nappies, the water, the detergent, the wash temperature, your environmental choices, even your LO's poo make a difference! You can get detergents formulated for nappies which are designed to rinse cleaner than standard detergents, which are generally made to linger in clothes to make them look brighter (optical brighteners) and give you that lovely 'fresh' fragrance.
If using a nappy detergent, start with the recommended dose for your water type and go from there. If nappies don't seem clean enough, use a bit more. If they smell of detergent use a bit less and/or rinse more.
If using a standard detergent, don't use fabric softener but most other detergents will be fine - some things like fragrance will void some warranties but shouldn't really harm the nappies unless you don't rinse them out properly. I'd start with less than recommended, maybe 1/4 or 1/3 dose and see what happens with one extra rinse. If they're not clean (you'll be able to tell as soon as they come out!) re-wash with a bit more. If they smell of detergent or the rinse water is sudsy, rinse again and use less next time you wash. It's a balancing act - obviously you want the nappies clean but you don't want residues lingering.