Change WordPress user roles and capabilities › Forums › How to or FAQ › Behavior of "Update" vs. "Update Network", managing 'local' roles › Reply To: Behavior of "Update" vs. "Update Network", managing 'local' roles
Answer to question 1:
If You press the ‘Update Network’ button while editing a custom role,
1) You save changes of the custom role to the main blog;
2) You overwrite all roles at all other sub-sites of your network with roles from your main blog. Of course after that you will lose all changes made to the roles at subsites.
If you wish to apply to all sites a changes made to the custom role only, go to the main blog “Users”-“User Role Editor”, modify custom role there, click “Apply to All Sites” and then click “Update” button.
P.S. I will try to answer on the question 2 tomorrow.