Voice Pot: Changes the voice of the the wah by changing the sharpness and making it more "vocal." The larger the value the more "vocal" the wah sounds.
Gain Pot: Really this controls the overall bass and gain of the wah. The lower the value the more growl and bass you'll get.
Sweep Switch (SW): This controls the sweep range of the wah. The larger the cap the more bass sweep you'll get. For instance the common value is 10nF, which i put on the board already, and the bass wah has a 68nF. Personally if I were making this I would start with the stock value and increase using values I liked up to the bass value, but hey, that's just me.
Sweep Pot: This will control the range of the week of the wah pot. No different then what you find on the Dimeback or Cantrell Wah.
R1: This will set the volume of the wah, the smaller the value the more volume you'll get. Typically it's 68k. So you can mess around with it and get as much or as little volume as you liked.