Sorry Guys, I am going to have to bow out of this one as it will be a week or so before I can get online again.
The answer to the last question, as gmat suggested was the awesome XB-70, two prototypes being flown, the other aircrafttype being the XF-108 Rapier, designed to use the same J93 engine.
Both aircraft were to use Zip Fuel to damatically extend range, but the whole concept of exotic, boronated fuels didn't work out.
Take it away, whoever wants.