You can move to page 1 and do a save as. That's not a bad thing to do on occasion anyway.
Would it still be considered the same chapter in the book file?
If you don't change the name.
Naw. It's easier to delete a period and put it back.
I've been with Adobe since the Nineties, in those days one was continuously surprised by new ways considerate Adobe developers thought of to make life easy for loyal customers.
I'll wait for rave reviews before I upgrade again. Perhaps the sign will be the return of show-off Adobe art instead of the bland and incorrect geometry of bureaucratic cubism.
I suggest the reason the older versions of In Design were so much smoother and more convenient is because Adobe staff published the great manuals that came with the software using InDesign, that was how the old Adobe Corporation found and eliminated irritating jerky quirks.