Roles Creator

Formidable Pro permissions will depend on what capability checks that plugin implements.

Regarding editing access for a single page, Capability Manager Enhanced does not provide a direct solution for that. If you give the role the edit_pages and edit_published_pages capabilities, those users will be limited to editing pages for which they are the author. But to prevent them from creating new pages, you’ll also need to make WordPress impose a create_pages capability requirement. If you want to go that way, Press Permit Core has a switch for it in Permissions > Settings > Core.