"Sample" Vaadin 8 project with 'Best practices'

Hi there,
I'm a new in Vaadin. I see the latest version is 8.0.3. I think the best way start learning from 8 version (not from Vaadin 7).

Have we a 'best practise sample' with Vaadin 8 project not for 'single-page' application? I need to create big project and still trying to choose best web framework for it.

And additional question about design WebUI. I saw in some samples that "web page" is described in '* .html' file.
Could any one describe this method of development.

Though a bit late, https://vaadin.com/full-stack-starter (part of the Pro offering) is exactly for this - a full stack example / starting point showing best practices for a larger project. As for the HTML files, they are Vaadin Designer layouts (also part of the Pro offering).