Dan,

We are working right now on figuring out how we could get the software to do exactly what you describe: import a csv file and have it update elements it finds in a depiction that match those in the file (as a function of an EID - Element IDentifier). An EID is how Depiction knows which element to "update" when a live report is received. The same mechanism might work when importing a file of data - that is what we're working on now.
One of the problems is that anytime you Add a file, you have to specify what element definition you want the added data to have. What would happen if you chose a different element type than what you did when you imported the data the first time. What if there are new rows in the datafile that weren't there the first time - you'd still have to choose the hovertext. And there are more functionality questions as well that need to be thought through before we resolve exactly how this might work.
For now, you'll have to delete the old data and keep using the Group Info controls to set the hover text and icon when the updated file finishes loading.
Our next update (due out in mid-Dec) will also include the ability to Export your Depiction data to a csv file. This would allow you to add new folks and edit existing folks right in Depiction and then export the data to a spreadsheet for loading into another program or another depiction.
Hope this addresses your question.
kim