A:
Not sure if you've gotten an answer on this yet.
Ducks calls come factory tuned, but some people (myself included) like to tweak their calls to match their calling style. To tune a single reed duck call, there's two ways to do it. First way is to trim the reed down to create a higher pitch call. Shortening the reed makes it easier to call as well. But be very careful about how much you trim off. I'm talking thousandths of an inch. Removing too much will reduce the volume of the call. Less is definitely more in this case. The other way is to sand down the tone board. Sanding will add texture to the tone board and make the call raspy. Use a fine sand paper (220+) and VERY lightly sand the tone board. You don't want to remove any of the material, just add a slight texture.
At the end of every hunting season, you should replace your reeds and corks as well.
Adjusting a double reed is a lot more involved and more trouble that what it's worth.