Thumbnails - documentation needs more information

The documentation is short on information regarding how thumbnails are generated and how the settings affect them, and the page itself is a bit ambiguous.

• The 'Thumbnails Setup' page shows a maximum size and a "quality of jpg compression" setting. It is not made clear whether the 'quality' refers to the image resolution/sharpness or the file size of the generated thumbnail. Does setting this number to 99 give me 99% image quality (resulting in a nice looking thumbnail with a large file size) OR does give me 99% compression (resulting in a horrible thumbnail with a tiny file size)

• What are the correct settings to tell the script to not alter original jpgs in any way?

• When you change thumbnail settings, does the script automatically create new thumbnail files, or is it necessary to flush/delete cached files? Which cached files need to be deleted...the ones on the server, or the one on the client/browser? Is it both?

• If the script doesn't generate new thumbnails when you change settings then how do you prompt the script to do this?

• The 'Enabled' checkbox and 'Default' radio button don't really say what they do. Does the 'Enabled' checkbox enable resizing for that particular thumb size, watermarking, or the entire thumbnail size label?

thanks in advance