Hi Livo
Firstly, I had a meeting with the Layouts developers this morning to discuss the issues raised by this ticket and there is a bug which is affecting Layouts archives that occurs when layouts are unassigned which accords with the errors you reported above, and that is being worked on now and a fix should be pushed fairly soon.
That will have complicated your experience trying to get this to work and I'm sorry for that. I'm escalating this thread and I'll keep you posted when there are any updates.
I realise also that how Views Content Templates and Layouts inter-relate can also be confusing, so let me cover that briefly.
Without Toolset, your theme's template files are used to generate the pages, and WordPress uses the URL (and your permalink settings) to determine which template file should be used when, e.g. single.php to render a single post, archive.php to render a post archive.
When you add WooCommerce it intervenes in this process to force using its own templates for single products and for the product archive (the shop page). (The WooCommerce Views plugin intervenes further, by allowing you to set whether to let WooCommerce use its template files, or whether to over-rule it and use the WooCommerce Views template files instead—so that you can then design custom product pages and a custom product archive.)
When you add Views to a site your single posts and archive pages are still rendered by your theme's template files, but Views can intervene and take control of the part of the page where the content is output (the post body when viewing single posts, the list of posts on an archive page). Create and assign a Views Content Template to a post type and it will be used to display single posts of that type. Create and assign a Views custom WordPress Archive and it will be used to generate the list of posts on an archive page. Only the content part of the page is hijacked, and your theme is still responsible for the rest of the page.
Now add Layouts to the mix.
If you are using Layouts with a theme that has not been integrated with Layouts then it will work rather like Views Content Templates and custom WordPress Archives as described above, replacing only the content area of the page with the rest still generated by your theme. You have more flexibility in creating the design of the content area, which is the main reason you might choose to use Layouts over Views templates and archives in such circumstances.
Finally, there is the possibility of using Layouts integrated with your theme. In this case Layouts is able to intervene earlier in the process of rendering the page and take control of the entire page and not just the content area, so that you can design the page header and footer yourself, for example, instead of these coming from your theme, and you can create different designs to use on different pages if required.
Layouts trumps Views when it comes to intervening in page rendering, so that if you have a Views Content Template assigned to a post type and you also have a Layout assigned to that same post type, Layouts will be responsible for rendering the content.
I hope that helps clarify how the pieces fit together.
