Flying from New Zealand to France - Stop over in Beijing

Hi,
We would like to go back to France and in the same time visit Beijing for a few days.
We would like to see the great wall of course and enjoy the city in general.. Would it be possible with a 72h stop over visa ? Do we have to be travelling with either Air China or China Southern ? Or can it be different company ? Does it have to be the same company arriving and leaving Beijin ?
Thanks a lot for your insight