I would like to shoot some Macro with my 500 C/M . . .

[Alexander6x6]

OK, if it doesn't tilt (or swing), then it won't affect DoF at all. I wasn't clear on that. Shift (or rise/fall) doesn't affect it anyway.
If the bellows offers no movements, it's really the same as variable-length extension tube.

In this case the shift movement is quite helpful to bring back the center of the image to its initial position after tilting.

 

[pbromaghin]

That 50mm macro on the X-370 is a great setup. My father-in-law used one on an X-570 to photograph the orchids he was breeding. As part of the MD system, Minolta also made an “Auto Macro” circular flash to mount specifically on that lens. I got one from KEH and plan to use the system, as you are, to learn macro photography. The flashes are $50-100 on eBay.