cant see exact seats on my system but from what I see economy looks like it's oversold however seems like a few seats left in business . Not sure if they upgrade but since your buddy works for DL he/she should be able to give you more exact numbers. Keep in mind that with my experience flying standby with Delta there ae usally TONS of people with higher priority waiting on standby so it's going to be tough especially with an oversold flight.

Suggestions? with a buddy pass you don't have much option except for the non-stop flight. A season non-rever would do ATL-CDG on Delta (2 WIDE OPEN FLIGHTS) then CDG-FCO on AF.