re: I’d like to be able to export all the data, revise it, and then re-import it using CSV Import. Is this a good idea?
Sure, other do it. There no way to remove entries though. You would have to manually delete them in Connections. I’d suggest doing that before you do the export.
re: I see there is no “Department” field available for export.
Which export tool are you using? It definitely should be included in the “All” export tool.