Nicolas and Jerome can better answer the ins and outs of how to use the native electronic goods plugin. But I wanted to mention in this thread that for more complex tax rules automation, Polished Geek has developed a HikaShop AvaTax service integration plugin. The plugin is going through the final certification approval process with Avalara now. Once the certification is complete, we'll be sharing more information for Nicolas to post on the blog and hopefully in the docs area. I wanted to hold off on that until we had final certification approval.
By the way, the plugin will be completely free to download. You only pay for the AvaTax service based on usage, and that can handle these types of more complicated EU VAT rules.