Yes, We can. Standard SAP itself has provided the feature.
But this is possible when the payer, payment terms are one
and the same for all the deliveries.

Yes this is possible in STd SAP settings ,provided all
header data should be the sames for all delivery's

Yes, We can generate a single billing document for more 
than one delivery. The basic criteria for this is as 
follows. The Payer,Billing Date,Payment terms must be same 
for the all deliveries.

Yes, Why not. 
All header data should be same for all delivery like Payer, 
Billing Date, Payment terms must be same for all the 
deliveries.

Yes, we can create, using VF04