Chris : I have added to the Canola backlog for a while now the "support" for usb and other mounted drives in the settings tab, but you will be able to do it even without it.

About the 50.000 to be honest the maximum we have tested was 16.000 songs

It's more about Sqlite than Canola, as most list uses lazy loading but getting covers will probably take a lot of time )) tip : uncheck all options but amazon before doing it

Marcelo