Capability Manager Enhanced is trusted to manage the permissions for over 80,000 WordPress sites.
PressPermit is the plugin for advanced WordPress permissions. You can completely customize your permissions.
The PublishPress plugin helps you organize and schedule content with a calendar and notifications.
PublishPress Revisions plugin allows you to approve, moderate and schedule revisions.
Multiple Authors is a plugin that allows you to have more than author for each WordPress post.
This part of the documentation has information about using your account at PublishPress.com.