[pkscout]

1) having the scraped artwork get saved in the artist's folder, rather than the addon_data\script.artistslideshow\ArtistSlideshow folder?

I don't really like the idea of cluttering up someone's music folder with artwork, especially without asking. So unless there is a sudden and large outcry to have the images stored somewhere else, they're probably going to stay put.

2) having the extensions *.jpg rather than *.tbn so they are easier to check; and xbmc has moved on from *.tbn.

Honestly, it's never come up. Storing them with the .tbn extension is how the add-on worked when I inherited it. I've been working under the assumption that it helped pre-cache the images or something. But if there's no advantage to it, I would certainly consider storing them in whatever format the source site uses.