UPDATE:
After trying a zillon code variations I came up with this very simple code which makes half the work:
<?php
defined('_JEXEC') or die('Restricted access');
if(!empty($this->rows)){
foreach($this->rows as $row){
$this->row =& $row;
$db = JFactory::getDBO();
echo $this->image->display($this->row->file_path, false, '', '','', 320, $height);
echo $this->row->file_path;
}
}?>
this renders the main picture for each product together with its file_path.
It works but I need to see all pictures for every product, not only the main one. I get this in other parts of the site but recycling the code doesn't work.
This code is included inside listing_div view trigered by a
Type of content Product menu.
PLEASE somebody inspire me!