“2 You have assume we are at the center of the universe, since we can see galaxies at that distance in all directions.”
Exactly opposite. It is assumed that the universe has no “center”.
Exactly! In my experience, the "center of the universe" question most often comes up in questions about where in the universe the Big Bang actually occurred. Apparently, they think that by knowing where in the universe the Big Bang occurred they can learn a lot more about the Big Bang itself simply by looking at that point in space.
BUT remember... one important thing about the universe when the Big Bang actually occurred... THE UNIVERSE BACK THEN WAS THE SIZE OF A PROTON!... and even smaller than that.
So... the Big Bang occurred EVERYWHERE in this tiny, tiny, tiny space the size of a proton, and you're not going to be able to find out anything about the Big Bang itself by looking at any particular tiny point in the universe today. It happened everywhere.