LHR Third Runway: needed yesterday. Probably won't be with us until at least 2015. Planning, legal challenges, Swampy brigade etc.
My only reservation is that the length seems to be "inching" up a bit; the original plan was for it to be about 2000-2200m (can't remember which) and now the latest plan has it being extended by a few hundred metres and I doubt if that will be the last. My understanding and hope was that this would be a runway for short haul aircraft, allowing easier feed to long haul flights, since short haul is being squeezed with demand for the current two runways. It wouldn't surprise me if, ultimately, the intention was to have the third runway at close to the length of the current terminal, in which case, short haul will ultimately be squeezed again.
As for T6, it is necessary, because without it, acft using the new runway will have to cross what is now 27R/9L and that will have an impact on operations on that runway; a new terminal close to R3 should avoid this.
As for the DC10/MD11, they definitely have three reversers, including one on the No2. I guess operation depends on the runway, but I flew j/s with Varig a few years back and was told that they prefer to use RT on 1 and 3 only, because if the No2 is locked or otherwise damaged, it would take longer to fix.