I like to say "Canon and Nikon are like Ford and Chevy, and Pentax is Studebaker". Hopefully, it won't go the same way.
Welcome to the K-01 cult!
Re: M42s: Do you have Auto-ISO turned on? With it on and a M42 lens, I think the K-01 is ignoring the mode dial and just shooting everything in "TAv" mode, where it adjusts the ISO AND the shutter speed (with a fondness for 1/125, it seems). It's not really documented (and has been frustrating for folks who are used to how older Pentax dSLRs work with M42s). After getting used to it, I found it so useful that I put some celo tape on the mounts of a couple M lenses to make the camera
think they were M42s. Just point, focus (or not, if hyperfocal), and click. Lazy, I know...