You don't have an ebay store so I'm not sure what you mean by storefront.
To add a log within your listing you would have to do that within the listing HTML. You might want to ask this on one of the technical message boards on ebay.com
Sorry but I'm not sure how to set up a slide show on a listing.
Just a head's up...you aren't allowed to give the url of another website in your ebay listings.