Thanks for checking it out Jumbo!
And thanks for pointing out the error for the 'facebox' modal function. I went over the code, but didn't find where to add the facebox js/css. Still it is a minor consideration at this point.
The Add to cart is working with the "Display modal popup upon 'Add to cart'" configuration disabled. If I enable it, the pop up works fine, but the product gets removed from the cart as soon as the modal window is closed. Clearly I can't have this happening on the live site. I can give you access to my developers mirror site if you'd like to see the problem there.
Thank you.
Tomas