Thanks for reaching out.
1.a The Masonry layout will not work if Theme Options > Ethos > BLOG OPTIONS > FILTERABLE INDEX is toggled on. Please toggle that off if you wish to see a masonry layout. And the page templates will not work on a blog page, Wordpress override the page you assigned as blog page and only uses its URL and name, but the page template in use is always the default blog template (index.php).
With blog layout configuration, you're only limited to Theme Options configuration.
1.b. I just checked and I don't see any redirection, it all links to each post page. Would you mind providing a video recording?
1.c With blog page, you can't, unless you'll do template customization related to index.php. Or simply create a standard page (don't assign it as a blog page) and you can build it with your preferred content. Like using recent posts element, or essential grid, or the grid to display your posts and group them. Or is that what you're trying to achieve? (custom listing page)
- Yes, as 1.c, you can add The Grid but not on the blog page, it's a reserve page used by Wordpress. And it uses index.php instead of page templates. I recommend just creating a page where you can add multiple grids and don't assign it as a blog page.
And yes, you can always delete them. Or perhaps, you can do some redirect from
community (assigned as blog page) to your custom page (where grids are added within the builder). Please check this https://www.wpbeginner.com/beginners-guide/beginners-guide-to-creating-redirects-in-wordpress/
Does the grid also showing the posts Ive written automatically in The Grid layout and can I use wordpress for the posts or do I have to use the grid always for adding new posts?
It depends on your grid setting, if you created a grid with the default setting then it will only display the recent posts that you added (newest on top/first). And you only need to add it once, unless you wish to display it on different pages. Please check this https://theme.co/apex/forum/t/extension-the-grid/74
Hope this helps.