Paul you've hit upon some big issues.
I am just finishing my first paid AC project and ran into all the situations you mentioned. Coming from VectorWorks I find ArchiCAD has most of the features I was longing for but I've been frequently bogged down in work-arounds trying to achieve the precise connections I was accustomed to creating using 2D only tools. Of course it's awesome how much is done automatically, and I could never go back, but a lot of improvements are needed before I'll declare ArchiCAD sections or elevations equal to my old 2D creations.
In addition to your excellent requests, the oft wished for ability for walls to show on adjacent stories would eliminate some walls we now draw and reduce the need for windows to operate across multiple walls.
Check out the thread I started titled Section/Elevation Parity for a related discussion.
AC26 INT, M1 Mac, OS 13.2.1
Yes, you read that correctly, we are in the US but use the INT version, because the libraries are better.