I think that my Firefox/Etsy drama is resolved now. Firefox suddenly quit on me and when it asked, I cleared my private data - again.
When it restarted Etsy was there just as it should be, and worked perfectly all day.
Support didn't get back to me after the first very fast response, which I suspect was a stock reply for people who don't know how to upload pictures to the site. I wonder if they will ever reply again. I bet not.
Anyway, alls well that ends well and I'm happy again!