.... It does not support ENCRYPTED DRIVES at the moment. Do not use it.
2. If the external drive has a ownership aware filesystem, like for eg. ext2/3/4, then the copy happens as ROOT without any interruption. You may change it later using sudo privileges and the chown -R command.
Note: To Shutdown the System properly, Click Exit Button on the Bottom of Desktop and Click OK to popup dialog.
it is SAFE to REMOVE external drives, AFTER SHUTTING down the system.
Check Screenshots. See Wiki.