Just to clarify about the News promo, it is all CG diarmy, as it says on the site link too. Hence Anne and Bryan were simply shot in an entirely green environment, with their hands probably resting on a green box. The computer composed studio set is just keyed in around them: a very accurate one at that.
The camera and studio floor appears to be an overlaid image from another studio - that looks like a standard pedestal camera rather than one of Studio 3:
http://mecridia.com/tmp/studio.gif
The desk is equally CGed of course (in any event the surface is way thicker than in real life), though it's not surprising there's no shelving or anything. It needs to be as spacious and flexible as possible to cater for multiple presenters and different setups. Indeed these roll-on, roll-off units were developed it seems to specifically cater for this need:
http://i2.photobucket.com/albums/y37/RTE1TV/RTNews-Wires.jpg
They often hold water cups to keep them out of shot (remember when Eileen had her choking fit she had to lean down?

), and probably the odd mic socket block too. They appear to be used on both sides for Six One, with the right-hand one rolled off set for Nine. The cumbersome design of the desk has its problems though, as the lack of support under the newsreaders' end results in rather embarrassing audible creaks - especially with Anne and Eileen who lean on it more than others.
Regarding the set, the plastic panelling does indeed pop out - for The Week in Politics. As mentioned before, this is how the current set design evolved: the chunky solid frame permits panels to be shifted about at ease for different schemes, as clunky as it looks for TWIP. It's odd that they went for solid panels and not translucent ones for this programme. This is also presumably what the two vertical silver strips are for behind the wooden frame in the middle - they allow manageable-sized panels to be shifted about rather than a giant one across the entire back wall. In any event, a giant panel would probably buckle in the middle, so they offer structural support too.