When you edit/create a hikashop products listing menu, you can access the hikashop options on the right side of the screen. In those options, you have an option to display the current category description. In the category description you can add images and text. If you want to add image scrolling modules in it, you will have to edit the file listing of the view product via the menu Display->Views and change:
echo $this->element->category_description;
to:
echo JHTML::_('content.prepare',$this->element->category_description);
In that menu Display->Views, you can edit any view of hikashop to suit your needs.
If you want to change products displays on listing, based on your changes you will either want to modify the product view files via that menu or, for less invasive modifications, edit your HikaShop CSS file in the configuration under the tab display.
You don't need to and shouldn't edit the files directly as your modifications will be lost when you update. By doing them via the interface, you will keep them when updating.