The others have pretty much covered it. We use prefolds and covers exclusively on DS (apart sposies at night, and the odd one when I'm out.)
4-5 covers will be enough. We have 5 and I wash a load of nappies every second day. You don't need to change the cover unless you get a poo leak.
I've never mastered the snappi fold - so always just used the tri-fold and found it to be pretty good. It's only when you get the GIANT poos that we've had leaks through to his clothes (maybe 2-3 times ever.)
We use micro-fleece liners with our prefolds. You can quite easily make your own with fabric from spotlight. The theory is they wick moisture away from his skin...
Having said all that, we didn't start using cloth until DS was 6 weeks old. There were a number of reasons for it (see
here for some helpful tips) but mainly because everything else was SO daunting at first I was glad to have one less thing to worry about! And, as mentioned, I still use disposables on DS at night. He sleeps 12-13 hours and I REALLY don't want to jeopardise that with a wet nappy wake up!
Like Lilfatty said, the sun does an incredible job of getting stains out - it's amazing the difference even 10 mins on a slightly overcast day makes!
ETA: Cloth wipes - I just made about 30 muslin squares - 4 layers thick, and about 15cm x15cm before DS was born, and they're still going strong...
HTH
Edited by Joscia