I think the ply color difference is due to the grain orientation. I'd want it in hand to be certain but I am not aware of other woods used on the early kits. Mahagony (Luan) was used later.
I assume the ply seam is at a slight angle, not perpendicular. These are the grandfather of the recording custom line.
Coated ambassadors are what I have on my D20 and black kit (top and bottom) but on the blue kit I run pin stripe top and clear ambassador on the bottom. These are great drums and will work well with any quality head choice.