OK...after several hours have solved the problem...
In the template_fullwidth.php file, delete everything between these two lines:
echo "<div id='feature_wrap'>";
echo "</div><!-- end featuredwrap -->";
Not sure that is 100% correct coding, but it works. The distorted top preview photo is gone from the page view, while the Featured Image still appears in the slider, correctly linked to the page.
This is the correct formatting of the code to include both posts and pages in the slider:
$additional_loop = new WP_Query(array('post_type' => array( 'post', 'page' ), 'posts_per_page' => 5, 'post__in' => array(37,50,54,30,32)));
As noted by Dude, the array numbers at the end of the line represent the numbers of your page. Change the order of the numbers to change the order of display in the slider.
I found that you need to make any posts that you want to appear in the slider Stickies, otherwise they won't show up. Don't know why, but that is what is needed.
I can now use template_fullwidth.php as the base template for a page that can be used similar to desktop publishing especially when used with WP-Table Reloaded plugin. And any selected page can be linked from the Slider, with the Featured Image displayed.