2. When I receive a signal through the Doppler I hear an audible tone from the antenna switcher on the rig audio. This isnt from the left channel input being played back through windows as I'm taking the audio feed directly from the rig itself as opposed to taking it from the sound-card, it appears to be the heterodyning of the two signals. Is this normal, is my circuit 'leaking' has anyone else experienced this?
This is normal - in fact, it is required for the unit to work.
Rotating the antenna (electrically or mechanically) causes the incoming signal to be modulated
by the doppler effect: higher in frequency when the antenna is moving towards the source
and lower in frequency when moving away. Since you are listening on an FM receiver, you hear
this modulation as a tone. What the software does is to compare the phase of this tone with
the direction of the antenna to determine, for example, which way the antenna is pointing when
the signal changes from increasing to decreasing. That is what determines the direction to the
signal.