1.How does the admin create and manage posts

Admin can create from Posts->Manage Posts 

Can create new posts from Posts->New Posts

Admin can  manage the footer pages from the backend based on their business motives  e.g. Be in a consent form of their choice or Terms and conditions etc

2.What are categories for Footer page?

Categories can be created for Footer Pages, so the footer contents can be segregated /grouped under a specific category

3.How does the footer contents appear in the front end

They appear on the footer based on the categories and pages created