[aiyodev]

Over the last two decades we’ve gone from not knowing if there were any planets in other solar systems to knowing that almost all of them have planets. We now know the second factor in the Drake equation is nearly 100%.

We don’t yet know the third factor yet, the percentage of planets capable of supporting life. But we do know about 22% of planets are small enough to possibly be rocky and are within the “habitable zone” of a star.

So a possible answer to your first question is that it’s likely 0-22% of stars have at least one planet capable of supporting life like that on Earth. This doesn’t say anything about moons or asteroids or the probability of life developing on a body that could support it.