I think the cost of fighting barbs in hammers, lost units, and unit upkeep make it worth it to make the Great Wall a priority. I forget when the first barbs appear. At our current research rate we would have Construction in 33 turns.
Of the victories we're allowed (cultural is prohibited) I think space is easiest. I wouldn't even know how to approach domination or diplomatic.
For a space victory I think we want these 6 cities for sure. The one in the mountains could be 2S and the one in Australia could be 1S. If you buy that and add 1-3 cities in Korea and Manchuria, that leaves leaves 1-3 cities to place.
Here's Manchuria, with a Corn that appears later and the Mongol spawn area. Some dotmaps:
* With Japan, on the Rice and 1E of the Wheat. Raze Kyoto and keep Matsuyama 2S of Kyoto
* Without Japan, Seoul and Corn/Pigs/Wheat, 1S, 2S, or SE of the Corn. Optionally add a city NNNW of the Corn.
* Without Japan, 1N of the Fish (on the Pigs) and 2N of the other Pigs
I don't love Seoul, partly because it has no fresh water, but it's fine, and it's cheap to capture if we want to do other things like pursue wonders. A settler costs the same as the Great Lighthouse, for example. If we want it, we should be sure to have a unit 2 tiles away when it appears.
2-3 cities in Japan would be great cities with great resources: Silver, Crabs, and eventually Whales. Japan spawns on turn 88, so we don't have time to destroy it immediately, but I think if we focus now, we could build something like 2 Galleys, 2 Cats, and 6 Axes and take it down before it builds many more units. That would put the Great Wall at some risk and probably make the Great Lighthouse impossible, but I think now is the time when our military and production capability will best outstrip Japan's. Or we could do it at Engineering or Gunpowder.
On the other hand, we could settle Sydney to get Crabs and Silver, as well as Sheep. The cities won't be quite as good, but it costs fewer hammers to acquire, is more stable with no risk of a respawn, and we can still get most of the resources. 5 heartland cities, 2 Manchurian, and 2 Australian leaves 1, which could be in northern Manchuria, New Zealand, or Jakarta. If we settle Manchuria and go light on military (like with the Great Wall) we'll probably get attacked by Japan, but you never know.
On Emperor I find it helpful to interfere with the leading civs like Germany and England. But if we turtle in China I don't think there will be much we can do. We'll be at the mercy of our own economic development and will have to squeeze every last bit out of it.
I think we should go after the Internet. It's hard even for strong a civ to get it, but I doubt we can win without it. If I'm right, this game is really a race to the Internet.
I suggest we think about what we want to do with cottages. I'm not a fan of running cottages without Medicine or at least Emancipation because of how drastically the plague downgrades them.
An interesting thing about Stonehenge is that we don't ever have to research Democracy. If we emphasize specialists and run Representation we could also skip Liberalism and probably Biology and Medicine. Every tech we skip helps. We could also research Constitution before Guilds, Banking, or Education (unless we bulb Education, then Printing Press) in order to win the Taj and get Representation earlier.
Even if we emphasize specialists, it might still pay to run Bureaucracy and cottage Beijing (Trading Company, maybe Opera House). Bureaucracy would also let us skip Feudalism until after Constitution. But Vassalage might still beat it, since units will cost a lot with inflation. It might also pay to cottage Macau, with the Stock Market and costs that force the science slider low.
Alternatively if we cottage spam, we could try to run for Liberalism instead of Constitution. Plagues would still wipe out our +2C Towns, but we could switch to Emancipation and make that a little less devastating.
If we don't go for Liberalism, or maybe even if we do, I suggest researching Meditation and Aesthetics after Calendar and trying to hook up Gold and building the Shwedagon for Free Religion. Running Confucianism might help with Japan or Mongolia, but it would hurt with everyone else, and I think we should pursue all the trading we can. Since we have Marble we might also get the Parthenon or the Great Library, but the Great Library can fall very early to Greece.
On the other hand, I think going from 3 happy to 4 makes switching to Confucianism right now worth it. We might still get the Shwedagon and be able to switch to FR without changing religions.
Thinking about other goals we could pursue, I don't think the conquerors event would do much for us. It would boost our power rating, but we can get the Aztec resources without it. If we also got Astronomy early, we could settle great American cities in place of good Australian ones, but then we would still need to go to Australia or southeast Africa for Gems. So on the whole I'm not sure I like the idea of pursuing the new world.