Personally, I have people disinfect their shoes (by stepping in a bleach solution) before going into my goat area in case they've been around other goats. (I do the same if I've been somewhere with other goats, also.)
The disease CL is transmittable to humans, so drinking milk from a CL positive goat is a bad idea.
You can make all those things from goat milk from any breed or cross breed, though some breeds generally have higher butterfat amounts and therefore make richer products.
How much they give depends on breed (for example, Saanens are known for being really high producers, but miniature breeds will produce less in concordance with their smaller size), the genetics of the particular goat (whether or not they were bred to produce milk or to be pets), and the maintenance of the goat (what it's fed, if it's wormy, etc). Weather can even effect production!
I highly suggest buying not only from a clean herd, but from someone who milks. I made the newbie mistake of buying from a show home to begin with, and then a not-so-serious-milking/pet home, and finally a REAL milking herd. All my animals are healthy, but not all are true milkers. I am now milking one doe who gives only 3/4 a cup per milking on her 3rd freshening and my "real milker" doe is giving between 1.5-2 cups per milking as a FF who kidded with a single. The difference in their udders is amazing, too.
