Let me repost this to see if I've understood...
connecting a turntable to CH1 with L/R in their proper connections allows audio to play through the mixer's master output on both channels, however only the RIGHT channel is produced in the headphones
reversing the input connections on CH1 (so the L from the turntable is connected to R, and vice-versa), the audio continues to play from both master outputs but now only the LEFT channel is produced in the headphones
the same thing happens when testing on CH2
you are currently using software, this was not tested with a regular ol' record or the LINE connections
Is that correct?
And yes, if you plan on using it with Traktor, you will need to own a copy of Traktor. You don't need to buy a copy from Pioneer.