Well, we have a resolution...
During my communications with the seller before escalating the matter to
ebay, I advised him/her of my 100% confidence that
ebay would resolve completely in my favor, and in accordance with my demands. I was right.
ebay refunded 100% of purchase price including shipping, and did not require I return the coins first. I remain happy to return the coins if I am compensated ahead of time for my shipping, but will assume after a reasonable time that the coins are abandoned, although not sure what I'll do with them, because I do not need them.
I indeed left negative feedback (first time I've ever felt compelled to do so), giving all 1 stars for the DSR's except for the one regarding speed of delivery, in which I gave 5 stars. The speed of delivery was the sole positive of this transaction. He/she attempted to rip me off in a real efficient manner.
For the feedback narrative, I left the following:
"Seller included pics of items other than those delivered.Details @ (Offsite URL shortening not allowed-9) /NcWbQW"
Thanks to all for your replies to this thread.