Let's say we want to see Earth as it was 1000 years ago. Assume that someone has set up a perfect mirror 500 light-years away, so that we can actually see the light that left Earth 1000 years ago. (That's a really big assumption.)
The best telescopes in the world can't see the Apollo landing sites from Earth. We didn't get decent images of the descent stages, which were left on the surface, until the Lunar Reconnaissance Orbiter sent back photos it took from Lunar orbit. See http://www.nasa.gov/mission_pages/LRO/news/apollo-sites.html
1000 light-years is about 20 billion times as far away as the Moon. There's no way we could see people's faces at that distance with current technology -- or with any reasonable future technology. (There are physical limits on the resolution of an optical telescope of a given size.)
And all this assumes that we have that perfect mirror out there. As far as I know, nobody has set up such a mirror for us, and all the light that left Earth 1000 years ago is now 1000 light-years away, badly faded, and beyond our reach.
It's conceivable that we could develop faster-than-light travel (which may or may not be physically possible), go out there, build a telescope with a really big aperture, and point it back at Earth. But that's not likely to happen any time soon, and I wouldn't know how to determine how good an image we might be able to get.
And going back millions of years just makes the problem worse.