Well physical laws might have differences, but if you know enough math that's something to check against. it's not exactly proof, but failing to falsify something is better than wondering if it's all a lie... or finding out that it is. That said, there's also shared knowledge between other...
no, it's not fucking obvious, a moving earth implies parallax which would be extremely difficult to measure without telescopy of considerable precision. the prevailing thought of the time was that the stars were much smaller and closer than they are now known to be, so the implied parallax...
The term used in the WN seems to be primarily 魔物 (that is, "Mamono", or magical/demonic creature).
In contrast to bakemono, majin, mazoku, yokai, kaiju, monsutaa, or various other terms that roughly correlate to monsters, demons, devils, ghosts, or other malignant supernatural entities.