The sub inboxes are a quick way for you to see how many people have replied and status they are in.
You can click any sub inbox to see all of the contacts in that status. Click on the contact name to review the conversation history. For Cycle and Follow Up you can click on the Cycle Interval or the Status to see what email is scheduled to be sent.
There are lot of things you can do to keep your meetings on track. See Meeting Management Article.