Hi
The smaller gauge you mention is a mortise gauge, I think ?
Ken
I concur with Ken on this one.
A really impressive tool cabinet. Who's is it?
Looking at your questions
All 4 gauges appear to have a different scribing tool. A better resolution pic might help.
The brass thing above the brace chuck does look like a set of calipers, for measuring diameter. There are other calipers made of steel in the box, but these look like that they may have a gauge attached for taking direct readings; but this is only a guess.
As for the disks, I cannot even guess, a better resolution picture might help.