Theming and Panels:

Most of the critical elements of display have template files.

You can just copy the template file to your theme
and modify it to suit. 

For example, if you'd like to change the search results page,
simply copy amazon_store_search_results.tpl.php to your
theme directory and modify.

The Item display page also has a complete panels implementation.
You can enable the panel and then mix and match panels
to suit.