I would like to add some extra button inside post and admin page creating plugin or adding hook inside functions.php. The image below resume all I want :

(1) depending to we are on wordpress post or page . Two buttons next to Update or Save (post or page (1)) button. First one allow to add a new (Post or page (1)) just after saving or updating the current. The second allow to go back to list (Post or page *) just after saving or updating the current.