I dry feta for 48 hours before brining. The brine is made of the feta whey, which usually has enough calcium, salt and acidity to match the cheese. If it doesn't (if the cheese starts to soften), or if you use a water-based brine, add in some calc. chlor. and some vinegar or citrus juice at about 1 tsp per gallon of brine.
Goat feta is usually softer than that which I usually make with a mixture of cow and goat milk.