Yes - though it's a little more abstract. Those 57 threads could be occupying the available cores in any number of ways to get to 247.9%

This is how CPU usage has been calculated across Windows, macOS, Linux, and the BSDs practically as long as multiple cores have been a thing.

Windows? Last I checked, the max is 100%. Pegging 1 core of a Core i7 shows 25%. Probably a more consumer-friendly way to measure. But 400% sounds cooler.

Yes, I believe so. It was pegging multiple cores.