In the ForceField subs, is the speaker level in signal split into high and low in the analog domain, with the low pass signal going to the DSP module and the high pass signal going to the speaker out terminals, or does the full range speaker level in signal go to the DSP module and all filtering done in the digital domain?

Passive High-Pass for the L/R speaker-outs. L/R speaker-ins are only summed, not filtered.

To make sure I understand, the analog signal going from the subwoofer L/R speaker out connections to the speakers has not gone through an analog to digital conversion at any point in the subwoofer.

Correct, just passive high-pass circuitry.