For physical objects basic unit is centimeter

When creating primitives from menu, you may specify desired unit (feet, meters, etc) but tranlations xyz remain in cm

Lighting system have pulldown to select unit properties(i.e., lumens/cm2)

For cameras, I have never felt need to convert when bringing in poser scene. I do delete the shadow cams and builtin cams (dolly, front, top, etc) that are not being used. I change the name of MAIN_CAMERA to something more descriptive (personal taste).

I have not noticed any difference in perspective or FOV in an imported viewed in DS