Yes, you need raw milk to make most home-made diary. Pasterised milk or restored from dried milk usually sold in supermarkets will not work in most cases.

You hardly will be able to make even tvorog from processed milk with long shelf life. Tvorog translated as cottage cheese or dutch cheese, but it is somewhat different - instead of some special bacterial culture or animal ferment you put a piece of fresh sourdough rye bread into raw cow milk as a starter, it curdle into beads in day or two at home temperature, then you filter that curd with fabric and it is ready. Slightly sour milk is fine for making tvorog too, so it is a common way to use surplus milk that start to sour.

Home kefir starter culture is transferred from generation to generation in families here too. Interesting, that different lines of starter have different taste. Industrial kefir culture is standard so mass-produced kefir you usually buy in supermarket or grocery will be more or less same, but homemade or farmers kefir will have range of flavours.