Since you have a DXS, I believe you're running wirelessly to a USB dongle such as a Spektrum WS2000. If that's true, then the reset function isn't mapped to any radio channels by default, as the dongle is limited to eight channels in total. With a little work you could set it up to function as a reset button, although you'll give up whatever the button might otherwise do (Panic mode on the few aircraft that have it, or also Thrust Reverse on a couple of others.)
To set it up, go into the Controller Profile and edit it. Scroll way down, past the usual RF channels, and the last section of the list is for "User Interface" settings. You can change "Reset" to one of the channels coming from the transmitter. Click the blue bar for Reset, and then press the button as directed to assign the button's radio channel to the Reset function.
As for the Switch B issue, you probably need to recalibrate your controller. When the calibration tells you to center the controls before you begin, that also includes three-position switches. Put the switch into the center position just like you would center the sticks, and flip it back and forth during the calibration.
