You mean this gallery?
http://demo.styledthemes.com/encounters/wp-gallery/
That is the default WordPress gallery function using their short-code (part of WordPress).
Regarding your second question….you would have to contact the shopping cart support you use to find out if they have a WordPress plugin, otherwise, you will need to check other options, ie: WooCommerce….but also contact them or whoever you are interested in to see if they can import your current shopping cart.
