Re the 1st Grenadiers badges:
First off, I’ll post pics of my marked K&S one later for comparison to yours. I not certain if Kirkwood marked all of their versions of this badge.
And speaking of versions of this badge, there seem to be quite a few. Several of which fall into the “suspect” category such as this one in my collection - pictured below. It is a very nicely die stamped example, and even has a ‘stabilizing pin’ on the reverse to keep it from rotating on the uniform. The spinner is looks just like the Societa Italiana/Medaglia type found on the 2nd Corps syrenka badge. Maybe this suggests an Italian maker for 2nd Corps issue? Veteran’s copy?