I wonder how many of these I will work through.
Anyway, assuming 10mm figures and with the first dimension the stand front:
Cavalry Regiment, both sides: 2 figures, 30mm x 30mm
Infantry Regiment, German: 8 figures, 40mm x 30mm
Infantry Regiment, French: 6 figures, 30mm x 30mm
Guns (2 batteries): 1 gun and crew 30mm x 30mm or 40mm depending on model size.
Division command will have to carry status information, so perhaps 40mm square or circle with a small command diorama and space for markers. Likewise for Corps and Army, perhaps with different shapes.
I am also considering "markers stand" to provide spacing for march columns (a wagon and marching troops on say a 30mm x 60mm stand).