Astronomical distances, light speed, and uncertainty

[MyshkinCommaPrince]

I'm hoping someone better-educated than I am can give me a reality check about astronomy. I'm genuinely puzzled, here, but can't figure out how to research this question using a standard search engine.

I've never had an astronomy class, although I have read some of the popular science books touching on the field. I've come to be puzzled by the question of the actual state of the universe, out there in our sky. Even in the science books and articles I've read, everything we observe through telescopes is treated as though what we see is happening right now. But the speed of light is limited, and most of the things we see are far away, so they happened a long time ago. When we look into the sky, we're looking into the past, and not one single, uniform past. Each star we observe cast its light at a different point in the past, as long ago as it is far from us, so to speak.

I had to arrive at this thought myself, never having seen it explained anywhere, and it really sort of blows my mind. Particularly when it is so consistently ignored. It seems like it should be an important point. But why isn't it discussed? Is it too mind-boggling for the average person, or is the point somehow completely wrong-headed? Am I wrong about the idea?

If I am not wrong, I see other questions arising from the thought. The longer ago the light was cast from a star, the less we should know about its current state. How certain can we be that any given distant astronomical object still exists, now? How sure can we be of its actual current location or distance from us? I've assumed that there must be some uncertainty about the state of the universe, which grows greater according to the distance of the objects. So we couldn't, say, create a Star Map based on what we see, then send a ship out at light speed and have any real idea of what it might encounter along the way. But is that correct?

I've been reading (and likely misunderstanding) one of Brian Green's books, and he explains how we can know the actual, current distance from the Earth of extremely distant objects. I expected him to end up touching on the thought I raise above, but there is no sign of it. He makes it clear that we can know where these things are, or at least their distances from us, without any difficult uncertainty from the age of the data. I assume he knows what he's talking about. I certainly don't, at any rate.

So... what's really going on, here? Does anyone have any idea how accurate our data and predictions can be, over astronomical distances? Have I fallen into some typical autodidact's trap with my reasoning? Can anyone shed light on the matter for me?