It's great that you're thinking about using reusable nappies.
Do give them a try. You might love them as much as I did!
Everyone you speak to about them will give different answers to your questions. This is a very personal topic and everyone deals with such matters in their own way.
I will start the ball rolling:
There are various types of nappies and they all have pros and cons.
Whatever you choose, you will need an absorbent part to hold the wee and a waterproof part to stop it wicking into the baby's clothes.
All-in-ones are nappies which have both parts together as one.
These are easy to use in the same way as a disposable, but they have the disadvantage of being slower to dry because the waterproof part cannot be detached from the absorbent part.
Pocket Nappies and Stuffables are ones with a waterproof cover which can then be filled with absorbent material and boosters. Once stuffed and ready they are the same as the all-in-ones, but they have the advantage of being separatable so that they dry more quickly in separate pieces.
It is also possible to buy nappies with separate covers.
These are slightly (very slightly) more time consuming to put on because you need to put two layers on separately, but they dry more quickly because the waterproof cover is not attached to the absorbent part.
Personally I used separates.
One reason was for easy drying. The other reason is that I used 'Birth to Potty' nappies. This meant that I could use the same ones right through from birth until my DCs stopped needing them. It is the cheap option as I didn't need to buy a whole set for each size.
I did have to buy covers of each size, but I only needed about 3 of each size so it still worked out really cheap.
I used Tots Bots and Easy Peasy Nappies with Mother Ease covers.
I was really happy with all of these.
The number of nappies you need depends on how often you plan to wash them.
The average baby will go through up to 10 per 24 hours in the beginning. I washed mine everyday, so I could manage with 20 nappies. I had one set to use and one set to wash and dry each day.
Some people have many more and only wash a couple of times a week.
You'll need about 3 wraps if you choose to use separates.
Do you need anything else?
You'll need a bucket with a lid to keep them in.
Some people put a liner in the bucket so that they can easily transfer the nappies to the washing machine from the bucket. I never used one and never felt the need.
You might also want to consider liners.
These allow you to remove any poo very easily and put it straight in the loo.
Liners can be reusable or disposable. The disposable ones can also be flushable or non-flushable. I have used all three types.
Flusable ones are easier than non-flushable, but I got frustrated by the wastage of disposables and changed to reusables, which I prefered.
You can also buy resuable wipes. (I used Easy Peasy Nappies wipes.)
These are soft, kind and also eco-friendly because I simply washed them with the nappies.
Some people use special detergent. I never did. I simply washed them all in the same detergent as my usual clothes, but without using much of it. Less is better to prevent them getting hard.
Drying them on the line really helps them to stay white rather than going grey.
When you ask how often they need changing, do you mean how often do you change the baby or how often to do buy new nappies? I assume you mean the former...
Probably more often than disposables do. People tend to leave their babies in wet nappies for longer than they should because they feel dry to the touch. With reusables you can feel more accurately how wet they are. Also, you know that you'll be using it again in a couple of days so it feels like less of a waste to change them more often.
How often you change them will depend on your baby and on the age of your baby so it's a difficult question to answer.
I'd say, take a look at
www.thenappylady.co.uk/index.asp
www.kittykins.co.uk/
etc.
Buy one of their trial packs and give the nappies a try.
You can gradually increase your collection and try different types to see what suits you before buying a whole set.