This site by chance answers a couple of questions that I had. One being how much the curd should be played with, and two about the butter milk. Sometime I nail the mozz/provolone just right, with no buttermilk lost, but yesterday I did something wrong and lost the buttermilk. I think I have worked out where I went wrong, and I am learning to "read" the curd much better.
Also they state that the water that it is immersed in also makes a difference to the final flavour.
So lots to work on here and experiement with.