[Mike O]

Regarding the highlighted part of your post. Let's say the CG offset produces a 5 degree closure of the leading edge. Using the plane of motion as a zero reference the leading edge will be 5* or 95* closed ?

I think I understand your question but I'm not 100% sure.
See if this answers it.

Using a golf example - say we take the direction of the clubhead movement at lowpoint. Let's call that line the target line. The leading edge is perpendicular to that target line if it is "square" to the target line, or 90 degrees. If the face was 5 degrees open let's call that 85 degrees and if the face is 5 degrees closed we'll call that 95 degrees to the target line.

So 5 degrees closed of square and 95 degrees closed in relation to the target line.

Let me know if I understood your question properly and if that answered your question.

Outside of your question I would say roughly - closures due to clubhead/face construction in relation to square based on the line of pull through the longitudinal center of gravity would be:
1) Greater as you move towards the wedges and less as you move toward your 2 iron.
2) The leading edge would be up to 20 degrees left of the longitudinal center of gravit for the wedge. That's not a correct answer - haven't measured it. might only be 10 or 8 or something. I'm sure we could measure it while we are hanging the clubs with our thumb and index finger.