These are very good points, silver! The reason for making the first turn 1000 years is just to age the pre-placed wonders, but the time scale needs adjustment.
As you point out communication trading is a key point. Right now it requires Printing Press (which nobody has in the beginning, even though the Germans have Gutenberg's Bible). The problem is that scientific civs sometimes get it as a bonus tech at the start. Once people get that - well, then soon everybody knows about everybody. For instance, Poland probably got the Aztec connection from the Germans, who in turn got is from the Spanish. And since the AI values maps highly, technologies are traded quickly. Nobody actually starts with Banking, but I suppose that some scientific civ, like the Germans or the Russians, that start with Education got it as a bonus and traded it to China. I can remove Education for China, Korea, and Persia, but I fear this will not change very much once everybody starts trading. Since the worlds is now connected, the techs will spread even without communication trading...
Firearms were introduced to Japan in 1542, which is why I didn't give it to them at the start. The Chinese have Gunpowder, but not the Koreans. I will give it to India!