PUL isn't waterproof, but water resistant. It should keep Seb's clothes dry as long as you don't leave it on forever. It's best to have at least two covers which you rotate with each nappy change to air out. I change Caty every 4 hours at the moment.
Wool, when lanolised (soaking in a bit of lanolin), evaporates wetness, turning the wee into water and salt, thus eliminating the smell. It's great. Caty goes all night in a wool cover. Fleece is the synthetic version of wool, but you don't need to lanolise it. Sometimes the wool or fleece will feel a little damp in the morning if Seb's a big wee'er, but it shouldn't actually wet anything.
It's important to distinguish between fleece and microfleece. Good fleece is the stuff you use for covers, it's thick, but microfleece is heaps thin and because it's water resistant, wee will get sucked through it by whatever's underneath (hemp, bamboo, cotton) so bubs will still feel dry. You use microfleece as a liner between the nappy and your bub's butt.
Maybe get a few pockets, covers, AIO's.....I have a range of them, it's best to try a few then make an informed decision. MCN (modern cloth nappies) have fantastic resale value.
There's a MandyMac website which you can google then read all their faqs.