When starting Super Duper...
 

Is the attached unmounted external drive supposed to mount? The reason I'm asking is that this morning it did mount and show up. i like to check the log every now and then. But after I quit SD and restarted, it did not mount again unless I used Disk Utility?

It won't mount when SD! is started manually, no, but it will mount/copy/unmount on a scheduled copy.