I have hunted in the SF bay my entire life. The shooting in pretty good if you get in the right spot. These days I hunt in the N. Grasslands mostly, it is a LOT easier : )
The types of ducks vary, you will get a few "regular ducks" every year (mallard, sprig, teal... that sort of thing), but mostly you will get "bay ducks" (ruddys, blueys, bufflehead and a few canvasbacks).
My friends and I shoot a lot of limits, so the shooting can be great although the ducks can be a little fishy tasting.
As far as where to go... There used to be really two options, one was to lease a salt pond from Cargill, build a blind and hunt there. The other is to hunt on the outside of a pond or in one of the many, many sloughs. Cargill has transferred all of the salt ponds to the federal government now so the rules are a little different but you can still hunt in most of them. You will need to look at the DFG page to get info on how to reserve a spot.
In all cases you will need a boat and most likely a dog. I have always used a 17 foot boat with a 35hp or 40hp motor. The bay can get big, bring enough boat.
Send me a note and I will send you my phone number. I can tell you where the good hunting is, where to put a boat in, even a couple of places you can walk to.