[pkscout]

Do you know of any advantage/disadvantage of having a separate unique folder solely for fanart as opposed to having ASHelper place the images directly in to your current Music Artist folder?

It's pretty much a personal choice. I separate my music from the images mostly because I don't want a folder of images hanging out with the MP3 files. From a technical perspective I don't think it makes a different.

Also, I assume that when "Image Priority" is set as "both", then AS will only download images that do not already exist in the <extrafanart> folder. Speaking from a bandwidth point of view....

I'm pretty sure that's the case. That's actually a chunk of the code I've never looked at much (I inherited the maintenance on this add on a few years ago). That said, AS only checks for new images for an artist every couple of weeks, so the bandwidth impact is likely minimal over time even if it is redownloading images.