Skye
AIO's are just that - all in one - no liners needed - unless you want one for easier poop disposal!!!!

I go through about 6 or 7 a day with each kid now - and a night nappy as well. But I change them basically every 2 - 3 hours.

So I would say that 12 would be a good number for you. Get reputable brands (ie - NOT from ebay) that you can resell on buy for baby when have finished using them. If you buy cheap brands, they may not work the way you want them to, you would have wasted money on them, PLUS, they won't have any resale value. JMO of course!!

If you have any specific questions - go into the cloth thread and start reading/posting all the girls in there.

ETA - sorry, didn't see your question about nights. I use baby beehinds bamboo fitted for DD at the moment with a woollen cover over the top. I use green kids minky times at nights for DS, plus Snoozywuns, plus bubblebubs GNST.