On the first case is pretty obvious that they are at least 5 images. (4+1 background)
You have a lateral and backlight where each consecutive group would cast a shadow on the group in front.
But some magazines are famous of actually taking a large group.
Take a look at this search https://www.google.com.mx/search?q=vanity+fair+large+group+photoshoot&dcr=0&tbm=isch&source=lnt&tbs=isz:lt,islt:2mp&sa=X&ved=0ahUKEwiH5faRrtHZAhVNylMKHZQ7B0sQpwUIHw&biw=1366&bih=700&dpr=1#imgrc=9KzusaYtQPz9zM:
(This is actually not one photo either but a composite shot to add the photographer and asistant into the photo), but you will notice that in a real group photoshoot they are using a "butterfly" light scheme. This is using a large softbox above the camera so each member do not cast a shadow on the next one. If they also use one below would be a clamp light scheme.
The lighting is the most complex subject here.
In regards to using a wide lens, no. If you want a quality photo you would not use one, but use a really large studio so you can go back far enough.
You also would not use a small sensor camera, but a medium format, so the focal length is not really small.