Most Xara users will incorporate shopping carts and the like via an iFrame. You can build shopping functionality of sorts, but essentially, as you say, Xara products produce static web pages. There is no inbuilt provision for data-driven pages, so generally people use HTML placeholders to include bespoke HTML.

There has been quite a bit of discussion on the forums about this kind of issue, as an experienced Xara user, where have you been?!

Welcome!