but we are therefore moving minutely slower than the speed of light, which, in a vacuum, is 299,792,458 m/s.
That depends on your frame of reference. But yes, granted, if you try hard enough you'll find a frame of reference where this holds true. Whether or not that frame of reference would be useful for any practical purposes is another question entirely.
My question is: If the earth is moving more than 299 million m/s, why when our path runs into rocks that are otherwise stationary is our comparative speed (velocity1-velocity2) only 72,000 m/s?
Because Universal Acceleration, as the name may hint, is universal. The only objects that aren't affected by it are those in close vicinity of the Earth, as the Earth effectively "shields" them from being affected.
But, once again, you demonstrate a lack of understanding of frames of reference. "Stationary" relative to what? The Earth? Clearly not. The Sun? I'd be sceptical too. So, what are these rocks "stationary" relative to?
It isn't viable to say that the meteors are moving at 299,792,458-72000m/s
I agree. It would be much more productive to use the Earth as the frame of reference.
because then all meteors have to be moving in the same direction with the earth and if, as can be predicted, not all meteors are moving in the same direction, and some must be moving in the opposite direction as us in which case they would collide with us at 299,792,458+72000m/s
No, in any frame of reference in which the speed of the Earth approaches that of the speed of light, you will find no other objects that have exceeded the speed of light. Special Relativity would apply to the meteor all the same.