Yes the import spreadsheet is what you need.
Exporting/editing/importing is for making mass changes (using notepad++ for example). Be careful, something like notepad or excel will usually change the encoding of the csv, and importing will not work. Notepad++ works fine.
An example of a mass change : you add a MiVB in a cluster, and want to rebalance resiliency => you need to remove the secondary element of dozens of phones, then add the new secondary element, quite cumbersome to do phone by phone.