Here's an update.
I decided to focus on corporations for the end of the game. I'm running well ahead in the score. I'm at about 2700 points. I conquered the Americans completely, have 17 cities, spread out mostly on islands, and am running Universal Suffrage/Emancipation/Free Market/Pacifism. The Mongols have 9 cities and are running State Property and have around 2000 points.
I am spreading Sid's Sushi all over the world and am able to run almost at 100% research. I updated many of my soldiers and a have a good navy with quite a few ships of the line and ironclads. I have steel and electricity. I am currently researching refrigeration.
My cities are struggling healthwise, even with harbors, aqueducts, grocers, and hospitals. The Mongols quit trading me dear. The Aztecs quit trading me corn and declared war on me. The Aztecs are hated by nearly everyone, have seven cities and a huge technologically behind army. The Aztecs have two cornfields, the only grains on the whole map. They also have cows on their lands, also the only on the map. They own the Pyramids in their capital. I could turn that into a city to make great engineers (for corporations). It would be nice for my future economy to conquer them. My cities would get an additional two health. Two allies are helping me attack the Aztecs.
I have a few questions:
1) What is the best way to switch my economy from what I have now to a wartime economy? Should I just switch from pacifism to theocracy? I did like the GP generating bonus, or should I just quickly try and make peace with the Aztecs? Can I carry on a war with pacifism?
2) I have little understanding of corporations. The world is rich in seafood but poor in grains. Should I conquer the Aztecs and take over their corn, would it make sense to start Cereal Mills?
3) I have been running 5 cities with forges and one specialist each to get great engineers, but engineers aren't popping out. I have no engineer producing wonders and Ironworks won't be ready for a while. What are other good strategies for creating great engineers to start corporations?
4) I have Wall Street in my capital. Should I found all my corporations there?