There is more info on the youtube channel, particularly on the Newborn Cloth Diapering videos.
You can use woolie wraps with flat diapers, prefold diapers, fitted diapers, or inserts.
Can you survive with less? YES! It just means you’ll do more frequent washing! Having more diapers, particularly in the beginning when baby is pooping/peeing more (and messier) and you are adjusting after giving birth or adopting you are running low on rest/sleep, it’s helpful to have extra diapers and covers on hand so that you can push wash day back 1/2 day or a day.