How to make a thumbnail slideshow when hover over album cover?
Here are my suggestions. You will need to load both preview and  slideshow, and hide slideshow with css/jQuery. Then with jQuery show whole slideshow on hover.

Or, you could use jQuery load() or other jQuery ajax methods to load slideshow dinamically on-hover, If the page has lots of content.

In any case, you will need to include some custom jQuery scripts in your page.tpl.php (checking if $is_front is true, to include some javascript via drupal_add_js for example). This is type of approach i use.

For slideshows, you can use jQuery scripts (i use http://css-tricks.com/anythingslider-jquery-plugin/ and http://bxslider.com/ ). 

If you are fond to php programming you can use content types and EntityFieldQuery to load elements in that slideshows.

If not, you could try and search for existing drupal modules to show slideshows like http://drupal.org/project/nivo_slider