Including a page in the sidebar/header/footer

The WP Text widget can display more than just text. You can put in images and links as well. Maybe that will work for you.

Hmm.. I was more thinking about including it header/footer, seperated from the sidebar too sometimes..? And also for this page to be edited by the WYSIWYG editor, and to add in images from the WordPress uploader.

You could edit the footer.php file in your theme and include a custom query to display a post.

..and hide that post from searching via search bar and category search and front page news feed?

How would I do that? ??

https://www.ads-software.com/extend/plugins/wp-hide-post/ might do it.