Meaning of Spike Viewer Graphs

I’ve started to explore the OpenEphys GUI with the stereotrode
example data that comes with it, and I have some questions about the
Spike Viewer.  It looks like it’s performing PCA for spike-sorting, but I
haven’t found any documentation that explicitly clarifies this.  Would
you be able to answer a few questions for me?

 -
How does what’s displayed on the waveform viewer relate to the raw
signal?  If I’m not mistaken, each electrode on the stereotrode has only
one channel, so I would only expect one waveform. Why are there five
waveforms displayed in the waveform viewer?  Are these the principal
components used to sort the spikes?

 – What is the x-axis on the waveform viewer and what are its units?

 -
What is the y-axis on the peak viewer, and what are the units for the
x- and y-axes on the peak viewer?  The x-axis appears to be spike amplitude.