Does the camera still work the aperture with an M42 to K adaptor?
No. With Takumar lenses the MAN/AUTO switch is used to close the diaphragm to the selected aperture. Lenses without a switch will have to be used at maximum aperture, unless the lens has been somehow modified.
I do use a digital device in my photographic pursuits when necessary.
When someone rags on me for using film, I use a middle digit, upraised.