I'm glad to hear they are helpful to you!
Yes - they are made for model space. Imported or opened? Depends on your workflow.
Layout? Now we are talking ...
If you work with QCAD on a semi professional base I would recommend to use them as a source to create a proper template. Those templates could content every basic what you need for new drawings like layouts, layer, blocks etc.. QCAD will duplicate those templates for new drawings (CTRL+N) - the original stays untouched ...
In my case I created a template for all my basic layer and blocks, a paper space for landscape and one for portrait prints. When I start a new drawing I have already my "personal" default setup and just delete at the end of the job what I haven't used. Yes, I'm lazy ...
My default setup for new drawing: