How to do such a layout AND how to structure pages/posts?

Hello,

I just found a web site using the Customizr theme. One hour ago, I did not know that theme. I hope some people here will be able to guide me…

A – Here is my first question: SITE STRUCTURE

1. As you can see on the screenshot, there is URL named Archives des Manga – 5livres
2. But if I click on the first image with the basket ball, the URL is then https://5livres.fr/meilleurs-mangas-basket/

Conclusion: The URL is NOT a child page of https://5livres.fr/manga/, which sounds a bit weird to me in terms of SEO structure.

Question: are all the articles collected and displayed on https://5livres.fr/manga/ there because of Category Tag? Or are they pages linked manually?

C – Can I get such a layout using Cutomizr free version? Is there customization needed?

C – How can I reproduce the same visual effect on the thumbnails/images?

Thank you.

The page I need help with: [log in to see the link]