Widgets on pages and posts; featured image as header

In order to utilize widgets on pages and post, I installed amr shortcode any widget (on the direction of support answers found here).

This works except that if you make the featured image for a “[shapely] parralax section for frontage” and choose background full or background small, no image shows up. It also appears there is still padding or margin on to the left side; it’s hard to say because I can’t get the background image to show up and the light gray background only shows up on Windows.

I would also like to use the featured image for a page/post as the header image.

There is a child theme available to do this, but it still repeats the featured image at the top of the post (so once in the header, and then also in the body of the page or post). Additionally, it adds a header image back into the homepage and makes the page not full width (so each widget on the home page is only about 80% of the page width).

Any help is appreciated. Thanks.