In his book, The Best Recipes in the World, Mark Bittman has several good recipes using them. The one for pork ribs braised with black beans and garlic is especially delicious. In some recipes you just rinse the beans; sometimes in others that call for sherry or Chinese wine (Shaoxing), you briefly soak them in that before adding. Good stuff. (By the way, remember to seal the bag well and store in fridge and they'll last a long time - since most recipes only call for a couple of tablespoons at a time.)

Cornstarch is the best thickener for this type of sauce. It should yield results that are closest to something you'd find in a restaurant.

I just smash them with a fork and a drop of water or two per teaspoon full of them. No soaking is necessary with the ones I use. I don't usually make a separate sauce. I just stir them into whatever sauce I'd be making in my wok (usually consists of tamari and a touch of rice wine or sherry, assuming aromatics consisting of some kind of onion, garlic and sometimes ginger have also been used; cornstarch slurry added if necessary, i.e., if meat wasn't marinated with enough cornstarch to make the sauce thick enough, or lo mein water + starch isn't enough). Love fermented black beans. ;o)

They are the same as fermented black bean. The sauce in this recipe seems to get good reviews. http://www.epicurious.com/recipes/food/views/Panfried-Tofu-with-Chinese-Black-Bean-Sauce-103384