... has been published on Timezone-Italy. It is in italian, but it is based on observatons by a few of the best Speedmaster people around, Gino Balbi and others
forum.timezoneitalia.com
In teh same site tehre is also a nice one on the push-buttons of Sppedmasters.
Regarding the crowns, what I know is that the second one you mention is the one used in all 2998s, and has a diameter of 6.7mm.
The third one I had never seen before, the first one is of later production.
Best wishes
Franco