For the first issue thats not realy true. To access the totp key you still need the actual device with the key, it’s only now split over multiple devices. Like having multiple bank cards for the same account.
For the seccond issue: Thats a good point, I have not found a good solution for that either, unfortunately
It would be, but thats because you already told it the answer to the original question.
Assuming you don’t know if 3307 is prime, if you ask it like this for any number it wil (almost) always say the number is prime.