1. The Germans and the Americans developed the area rule interdependently, and the concepts merged after WW2.
2. The XF-91/92, predate Whitcombs supersonic research. The XF91 max speed was mach 1, so it was not likely an issue.
3. The F102/106 did not originally incorporate the area rule and had difficulties at the sound barrier. The YF-102/106 did and speed through the barrier, the 106 being roughly 2 times as fast at Mach 1.6.
4. Yes the area of the intakes count, as a function of the nose break. You have to factor in the nose section.