In 2 and 3, Rashi explains that Hashem would have given the mitzvah
to Moshe anyway, but because the questioners were tzadikim (righteous
people), the mitzva was given through them.
In 1, I don't remember anything explicit, but in the story of the copper
snake,
Aaron told the Angel of Death that Moshe didn't do anything without
Hashem's OK [Medrash? -- YM].
Behatzlacha rabba,
Yisrael