The other reason I took an interest in your post, R, was the preparation to negotiation in Bullet Item 2. I did read "Never Split the Difference: Negotiating As If Your Life Depended On It" by Chris Voss. It was fascinating, and I read it just for pleasure and never put any of his advice into practice.. I regifted the book to my daughter and she took an uncanny interest in it. But AFAIK, she never negotiated anything out of me, at least not that I'm aware of.

There is training in negotiating available according to these search results.