DSP vs. non-DSP is not the same as analog vs. digital or coax vs. 6 pin

DSP is digital sound processing. Your vehicle either has it or it doesn't. Easiest way to tell (as you noticed) is via the onboard menu - you have a DSP option, so you have digital sound processing (an eq and couple other features).

The other points you reference all refer specifically to how the cd changer communicates with the radio or amplifier to give it a signal. There is the "digital" method, via coax or the "analog" method, via 6 pin harness. Both are functionally equivalent in that they provide a signal to the amplifier that it can then modify.

The "DSP adapter kit" is actually an analog to digital converter, and is used only if you have the coax cable installed. Since you have the 6 pin harness, you have no need for the adapter kit.

I also do not have DICE, so no luck on #3 ...

d-