Thanks for the meaty post. Fun!

To paraphrase a movie I watched WAY too many times when my son was young: I do not think you are as old as you think you are. Little surprise that EK wasn't using ammonium bromide when you were there.

A couple of times recently you have alluded to ammoniacal emulsions being obsolete technology. I've never run into that tidbit anywhere else, so I assume it is one of those proprietary things (??) Another silver solvent? I don't read much beyond the mid-70's. After that date, the literature becomes pretty much meaningless for the home darkroom, so I can easily believe I've just missed the "breaking news". Anyway, would love to hear all about it.

For the micrographs of crystals you've posted, what are the indicators of "quality"? I see differences in crystal structure. Is there something else? The third image is very uniformly octahedra. That's cool, but a little boring. Is this likely an emulsion that is intended to be used with other, different-structured emulsions in a final, multi-layer (or blended) product?

In point #1, I'm guessing you mean Na and K chlorides, as for, in general, paper emulsions (??). Are there many NaBr negative emulsions? Also, in point #4, most regular readers of this forum know you mean the halides used for the bulk of the precipitation, but don't forget iodide on your list of "survivors."