The Impact Home Template can display any number of panels the panels described in the main page documentation. It has options to hide its standard page content and breadcrumb.
Carousel
The first related feature group can be displayed as a carousel. This behaves in exactly the same way as described in Page Header and Top Level Menu. The carousel can be hidden by selecting "No" in the "Show Carousel" option of the article extras. This setting overrides the carousel options in the subsite configuration, allowing articles using the Home template to display a carousel when they are disabled elsewhere on the site.
If you choose not to have a carousel, relating a feature group to the homepage won't do anything.
Breadcrumb, Heading, Introduction Text and Content
The heading, introduction text and body text for the Home template are hidden unless the "Show Article Content" option in the article extras is set to "Yes".
The breadcrumb is hidden unless the "Show Breadcrumb" option in the article extras is set to "Yes".
These elements would normally be hidden on the site homepage, but you would want to show them if you were using the Home template elsewhere in your site.
Article Panels
Any number of panels can be displayed beneath the carousel. How a panel appears depends upon how the article that provides content for the panel has been configured, as described in the Impact Panels article.
Other Related Assets
The Home template is not designed to display other related assets, like links to forms, external links, polls, feature groups or media items.