I'm pretty sure I figured out the Bias frame problem and low shutter speed problem. The changes are in my fork. I'll field test it tonight and if all goes well, I'll submit a pull request.
I really have no idea where to even start with your cigarette lighter adapter problem. Seems like some sort of noise, but then why is it only affecting the native driver? Did you say pktriggercord worked with the cigarette lighter adapter and Ubuntu? I wonder if it has something to do with the SDK for PTP mode. It's possible we could try to compile the indi_pentax driver without PTP mode support to test, but it'd be a bit time-consuming.