Tab Groups bookmarks: are they worthwhile and reliable?

I'm now using Tab Groups more often than not, some for particular areas of work, like working with a particular software package, or for personal matters, e.g., one for travel, one for health etc. This seems to work quite well, easily switching from one big mess to another without mixing them all up.

I also have my bookmarks grouped in a similar way in folders—indeed, been doing that happily for yonks, long before Tab Groups showed up. Where I've created a Tab Group that corresponds to a folder of bookmarks, it would seem logical to migrate these to become Tab Group Favourites. This raises a few issues: –

1. 1. Other than convenience, for me a big reason for bookmarks is having a reminder of where to find some pearl of wisdom that would otherwise be a needle in www.haystack.aagh. How easy is it to inadvertently delete Tab Group Favourite bookmarks, possibly never to find said needle ever again?
   2. The little slider control icon bottom right of a new tab in Safari gives an option to have tab group favourites appear front and centre at the top of the new tab. This would seem to be a obvious choice and likely the way forward—why did Apply "bury" it there (I'd not noticed it for a long time and only found it by accident) and why did they not have it checked by default when adding a new tab within a Tab Group?
   3. I'd now like to copy bookmarks from a folder in favourites, or copy the whole folder, to the corresponding Tab Group Favourites, either using the sidebar or Safari menu Edit Bookmarks. But there seems to be no way of pasting them there, although dragging and dropping works and makes a copy. Is there a better way to do this?
   4. Is there not an Apple page/blog/post somewhere explaining how to do all this kind of stuff and get the most out of Tab Groups and Tab Group Favourites?