Directory Site Install Questions

I have a multisite network install. Will be having one site for a Directory. I see that a theme is provided within the plugin folders.

Now, that default folder for the directory. Is there a child theme available for it. or do I need to make my own?

Once a directory child theme is installed and network enabled, is there anything else needed to use it?

General question about child themes, and admins changes to global admin changes, i.e. Footer Text global changes.

Are the global changes by the network admin, do they apply regardless of whether the individual sites on the network, use other themes, including child themes or not?