The Russian meteor was about 50 feet diameter and nobody had a clue it was coming.
Stop it with the sweet talk!
It’s kinda like artillery whistling overhead. If you hear it, it isn’t for you. The next one might be, but not this one. Not as comforting a sound as you might wish it to be. 
Hardly that fast. Something around 20 seconds is typical for meteors, although the exact time will depend on the intial velocity and the angle is enters the atmosphere. Also on how high up it is when it explodes. Still, one second is way too short a time for just about any meteor.
Earth’s orbital speed is 30km/sec. So that’s a ballpark for a meteor crossing earth’s path at a right angle. Obviously the atmosphere will slow it, so the last few km will be less velocity. So minimum 5
sec, probably a decent amount longer…
We can’t even tell where decaying satellites will fall.
Try back in another century. I don’t know which one.
If it’s true that we wouldn’t be able to do anything about a planet-killer, it’s probably best that we not get advance warning. Can you imagine the rioting and random crime that would occur if people knew the world was going to end in a week or two?
That’s a very different case - we have a very light (by comparison) object with a variable cross-section, slowly descending on the atmosphere, which also can expand (become denser at high altitudes) depending on various solar phenomenon. It’s like trying to decide where a car skidding on ice will stop, versus where a car going straight with full power on dry pavement will hit the tree.