I think I know the answer to the first question. I believe there is the possibility of ordering additional middle coaches from Hyundai/Rotem to lengthen the 22000 sets. I believe this is only about adding capacity to existing services, not about new sets for additional services. I'm not sure if this is just a possibility, or if the cheque has been signed.
I agree with all your other points. The only questions being asked are about adding capacity to the existing services.
It mentions a rise in train usage to 75 million journeys over the next 6 years. 41 extra coaches certainly won't be sufficient to cater for that.