Hello, Ash.

The first thing I would recommend is checking the page source of your site, because the JSON/LD should already be in there; it was added to WP Core some time ago…

But to answer your questions, I do not have any videos, but I would be surprised if there aren’t some out there.

As for adding schema markup inside the WP editor, you might find that you em>can’t add the script there (WP natively blocks <script> tags in the editor), but if you can, and that works best for you, go for it!

My only concern for this method would be having to make edits twice; I am a big fan of the DRY approach. And, once you enter your content into the editor, it is in your database, so why not let the framework build that schema block for you?

As for the placement of the schema markup (in the header, content, or footer), it doesn’t matter. Since it is only for bots, they will find it wherever you decide to put it.

I hope this clears things up a little,
Atg