spacing after punctuation

users
#1

I don't know what publishers you are looking at, but all of the
publishers whose submission guidelines I've read, have requested files
in MS Doc file format. (FWIW, I've read over the submission guidelines
of over 100 publishers in the last year.)

You missed the context, which was the format publishers use for layout and
which they asked contracted writers to submit in -- not the format they accept
for submissions.

I think the avoidance of true small caps and old style numbering has more
to do with the practice of font creators, most of whom omit these features.

That might be true for FLOSS font creators. It is not true for the
foundries whose fonts are in the 4+ digit price range.

That's a very rareified category of fonts. Look at Adobe and other popular
foundries, and you'll find that including small caps and old style numbering
are rare enough that, when a typeface does include them, they are major
selling points.