As far as the lug nuts/studs, that was standard practice for some brands through the mid sixties to have left hand thread on the driver's side. Some heavy trucks stayed with it until the mid eighties. The theory was that the torque of the wheel turning forward on the driver's side would loosen the lug nuts....

To remove the lug studs, a broaching tool would help. Material from the drum is peened over the stud to prevent it from loosening up through abuse. See attached video;

https://www.youtube.com/watch?v=mi_FrxpeSi0

Also found this good video of the brake adjustment on a GPW.

https://www.youtube.com/watch?v=RKlIszhs-gE