[DTV]

I could be wrong but I believe reading that the cameras in D aren't on tracks, so presumably any repositioning of them would have to be done manually.  Whilst fine for regional news bulletins it's not ideal of a rolling news channel, where you may have guests coming in and out of the studio throughout the day.

They aren't tracked, but three of the four cameras have fully robotic peds (i.e. can move of their own accord) and the other one has a remote head (which was the situation in N6), so it wouldn't be super difficult to have a news channel from D for an extended period. That said, both in C while E is refitted would be the route I expect them to go down.

As for work on E causing disurption in the newsroom, I wouldn't expect it would be especially disruptive - as Newsroom said, the newsroom was in operation while E was still being fitted out last time and it's stage door is round the back. I would also expect the separating glass to be reasonably soundproof.