By this standard, it is impossible to know that any thing survives for any time. The OP becomes an unanswerable question for atoms and for all other things.
You can’t trust atoms, anyhow. They make up everything.
Yup, that’s the whole point of indistinguishability.
The “same electron” or “same nucleus” ontological stuff is rather beside the point. Indistinguishability ties to the quantum statistical behavior of particles, but that doesn’t mean you can’t talk about that electron. It is perfectly reasonable to say that you have an electron here and another one over there, and through observation know that they could not have reasonably swapped placed through transport. And that is unrelated to their statistical indistinguishability.