I have a client (actually their IT guy) who is asking for “FTP” access to their WordPress site. He is saying the “client” admin role we have given him doesn’t allow him access to changes he wants to make for SEO, plugins, etc. Is this possible in our Multisite installation set up? We can’t give him the same Admin permissions we have because he would have access to all the sites.
Absolutely no FTP access to the WP server. (Maybe give them FTP access to a very limited folder, but they can upload files directly from WordPress, it has media import features).
One of the huge benefits of WordPress in Multi-Site mode is you as the Super-administrator control whether Administrators can install plugins and themes. (Installing plugins and themes are key source of security holes, system crashes, trouble.)
SEO by Yoast is well recommended, and I’ve been using All-In-One SEO.
There is an option where you can allow individual site administrators to enable plugins, from among the plugins that are installed by you.
In /wp-admin/network/settings.php you can “Enable Admin Menus” that let a site owner change which of the installed plugins are activated.
In /wp-admin/network/users.php, hover over a user and click Edit, to “Grant this user super admin privileges for the Network.” (use this for people in your company who are developers, never for customers)
Normally users can only be Admin only for the sites where they are registered. See http://codex.wordpress.org/Roles_and_Capabilities for a Summary of Roles. Notice the differences in Roles for Multisite vs single site.
Administrators in Multisite can activate plugins and change settings, but not install or update them. Create a user with Administrator rights for a site (do this logged in as a Super-Administrator), experiment with what they can access.
If you really need more flexibility than the default, which I doubt, try the User Role Editor WordPress plugin.