Understanding the possibilities of Library Overrides and Data Organization across files

Hi there! This is my first forum post here :-)

I am very interested in grasping the usage of Library Overrides. From the perspective of organizing data, it seems awesome to have different blender files for different (animatable) characters and objects. And there would be separate "scene files" into which you link those characters and objects. Each time you make improvements to such a character, like refining the mesh, it is updated in all scene files that linked the character in.

I see the following interesting things to grasp in this domain, and for which a Course might be great to set the fundamental understanding and expectations:

• How to add the Library Override? 
  • On which level is it added? On the rig, the collection, on nested objects like meshes? 
  • Or are Library Overrides so general that they can be added anywhere? Is there any strategic advice?
• What are the "limits", and when does it "break"? 
  • For example, suppose we link a character rig (with a mesh) from one file, and we already pose it in a scene using a Library Override. Am I still allowed to add an additional mesh to the rig (say for a hat or sunglasses)? Does that also work when I had added several instances of that same character in the scene, will they all get the new clothing? 
  • Moreover,  can we still add or delete bones in the linked rigs? I might understand that if we modify the control bones then the pose of the character in the scene file can be broken. But if we add or delete deformation or mechanism bones, then the "interface" of the control bones could be preserved and the pose is not adversely affected.

I am eager to learn more about all this stuff :-) It seems so interesting to work iteratively on characters and scenes at the same time. Because, if the Library Override system is somewhat tolerant to changes in the linked files, you can revise your characters while you are already using them. This is very appealing.

My main question is maybe: is there a recent Course about or mentioning Library Overrides? I think there is a whole universe to explore with this topic. Or if my questions can be an inspiration for adding a new Course, feel free to use them as a starting point ;-)

Thanks for your help!