I would like to say that while it is possible to use a little trig and algebra to solve for the angles, like you asked about, I'm not real sure how effective it will be.

My math professor last quarter in analysis was found of telling us how he believes mathematics have no real world applications,,,lol...it is possible and in fact I enjoy thinking about the honing process in terms of how you could apply math to the process. So you could certainly use math to answer these questions but....

Having said this I think it is far more important to simply understand the geometry, trig, etc. that underly the process rather that trying to actually measure the quantities. The imprecision involved in any measurement is really going to be a problem in making calculations like how many degrees will the bevel change with one layer of tape vs. two layers? Using micrometers and the such will help, but how much? I mean is electrical tape perfectly consistent in terms of thickness? Is the spine exactly uniform in thickness and perfectly flat? The answers to these questions is probably not, but that's O.K. because they are close enough that this process works.

The entire honing process eventually comes down to what "feels" good enough for the person shaving. It would be nearly impossible to actually quantify this experience in numerical terms. Although you could just divide the spine by 2 and use tangent, sine, or cosine with the length of your blade to calculate the bevel angle; who says this angle is "correct or not" this may shave great for me but someone else may disagree. I think the fun in honing comes from finding the edge that suits me just the way I want it, to that extent I'm not to worried if end up at the same angle the blade was set to in the factory or by whomever honed it prior to me. I'd like to set it to where I think it feels best. After all its my razor.