Meints Michigan Railroad Atlas which is a 5 volume set.
Hannum In the Pines - An Atlas of Michigan Logging Railroads.
Yes they cost but they have a lot of material that can help answer at least some of these questions.
The short summary is there were many logging lines in that area. Following grades in that area can be problematic without consulting multiple references.
I found it most interesting that it was a European that put together those SPV Atlases.