Skills and Tools in ICM

Hoping to get a few questions answered on skills/tools based on the resource materials and examples from the classroom.

Do you guys keep a "global skills" folder at the project level (ie. for skills used for multiple workspaces)? That way you don't have to maintain the same skill in multiple places?
In the workspace-blueprint example, it says "skills work best when they're wired into the CONTEXT.md files. I asked Claude how to "wire" (which I assume just means making it accessible via backslash) and Claude said it needs to exist in the .claude/ folder, but I don't see this in the example.
The example also states "you can wire up to 15 skills per workspace". I don't see this limitation in any documentation - is this just a suggestion? If so, why? If you invoke a skill by name or md, why would you want to limit the number of skills in a workspace - if the ICM works as intended, it should only load in the specified skills.