For a Facebook Page, you need to grant the following permissions:
manage_pages
publish_pages
publish_actions
For a Facebook Group, you need to grant the following permissions:
user_managed_groups
publish_actions
If you are trying to setup a Channel for a user who is not an admin of the Facebook Application, you'll need to go through the review process with Facebook to allow your app to request those permissions. If the Channel is for an admin of your Facebook App, you don't need to go through the review process and should be able to grant those permissions when you authenticate. In this case, there *will* be a warning like "Some of the permissions below have not been approved for use by Facebook. " However, you only need to submit for review if non-admins of your app will be needing to grant those permissions.
I hope that helps explain,
Alex