DW is a vegetarian,and as such I use the vegetarian rennet. I prefer the animal rennet,since it takes less to make the same amount of cheese,as you do with the veg. type.
The liquid that separates out is whey. I keep a gallon on hand,cold and flavored with fruit juice,as a protein drink that's better than that caffeinated sugar water,that is sold at the grocer's. Also,whey can be for substituted,one for one,water,in bread recipes. This whey is fine to use with whole grain breads and adds significant amounts of protein to help build the gluten so the bread will be less dense.
Leaving fresh cream,in a shallow pan,overnight on a far corner of the wood stove (after the stove's been banked down for the night,) is called "clotted cream" and is kind of like butter but not. It's good on fresh biscuits in the morning or cornbread at suppertime!
The minimum amounts of cultures and rennet you must order,at first,from "Dairy-Connection",may seem to be a bit much. If kept in the freezer,it really does last a year and I go through a few orders in a year's time.
All y'all take care.