Let's say I'm uploading a directory with 20 image files and 15 HTML files. After adding the directory to the queue, I'd expect that 9 of the contained files would be transferred simultaneously. Can I actually see 9 files being uploaded in the queue? Do I have to drag and drop each new file or directory in order to start a new batch transfer so that more than one file will be uploaded at the same time?
That's the only way. Anyway most SSH server does not allow you that many simultanous connection. And remember that opening session over SSH is costly (comparing to FTP).