Default number of segments is 12 for arcs and 24 for circles. Very often for me it’s too much (for visual and performance reasons). If there is a lot of arcs/circles in the model and want to change the number of segments in all of them or in all future ones you can’t do this. You have to do this manually and remember each time you draw a arc/circle to set the proper segments value. It’s really tedious and annoying.
Add an option to set default number of segments for arcs and circles in Model Info window (for each file).
IIRC if you draw an arc and circle in a template file, delete them, and save the file with all other things you want (tags, scenes, materials) the settings will be there when you use the template.
Unfortunately not. At least not in the Windows version.
If you create and save the template as you suggest, then quit SketchUp and restart with that template arcs will still have 12 segments and circles, 24.