Create a 'Want' button that drives traffic and sales by automagically linking to a social wishlist on the Facebook Timeline.
No! Just insert the shortcode with the proper values and you're done!
If they have a Facebook account (and it's more than likely that they will) then all that they will need to do is authorise the app the first time the click on the button. That's all!
Yes, for now the image url is required. This is the image that the visitor will see in The Want App's overlay.