I hate to Pee on the cake chaps but I think you'll find that the Germans were the first to regularly break the sound barrier albeit with an unmanned vehicle. Ask any one who was in the South East of England or Antwerp towards the end of the war. The most unerving thing about the V2 was how the sound of the thing arrived after it had landed so to speak. The Idea of an all moving tail plane had ben theoretically postulated by German Scientists quite early on during the war. Whether it was for research on the V2 or not I can't say, but the Germans had a number of very sophisticated supersonic wind tunnels during the war. In fact the Germans had a great deal of data amassed concerning transonic and supersonic flight most of which was seized by the americans during "Operaton Paperclip" (I think)
I also seem to recall that the all moving tail plane was some what of a lucky accident. I can't remember where but in a book about the X planes I rember a quote from an engineer who said something along the lines that the original tail surfaces were conventionally arranged, however there was a provision to alter the pitch of the horizontal stabilizer using screwjacks. After a number of transonic flights it was found that the pilots were unable to hold the forces by hand so a modification was made to allow the stabilizer to be moved in flight. This was found to work so well that the elevators were locked off and the screw jacks used for control at all times. I'll see if I can find the source to back this up.