I am sorry to report that I do not understand the ramp angle. Brian wrote that code, and I really hope I never have to dig a bug out of it, because it is strange code.
I believe the ramp angle refers to the slope of the ramp the tool follows down- 90 is a straight plunge, 10 seems to take a long slow ramp, in one circle case it took more than one turn around the circle to get to full cut depth.
Best way to see it is to try a few examples, just changing the ramp angle, then use the preview button to see the code and the tool path.
Dont ask abut Ramp Dist- as far as I can tell it does nothing. Ill try to get Brian to explain it all to me someday.