Many thanks for the answer!
I have another question: sometimes conquered cities cannot be kept, they get razed automatically. I've come to think this happens to size 1 cities; is this so or are there any other factors involved?
If the city is size 1 and it has not yet accrued enough culture for a border pop, it gets razed. (Not sure what happens if the city has been larger than size 2 in the past.)
Does money from specialist merchants go through the research/gold slider or does it just get put through markets and banks and such? I'm just wondering if you can have a city or two with lots of merchants in that essentially pay for all your other cities. On Vanilla, if relevant.
Important distinction: merchants give
gold, indicated by an icon of stacked coins, which can be used to purchase things. Cottages and the like give
commerce, which cannot be used for anything directly but is instead turned into research, culture, gold, and espionage via the sliders.
Banks and the like give a bonus to gold, so merchants' yields go through the banks.
If you want to try the tactic you suggest, make sure to do it with a city that has a massive food yield and/or loads of Cottages, Bank, Grocer, Market, and Wall Street.
Kleen, the peace treaty that got cancelled: whenever you make a deal such as open borders, the game automatically creates a peace treaty between you that you cannot break. This is to prevent abuse of such deals - just in my previous game, I was just about to wade in and kick Brennus's arse, and he actually
asked me if I wanted open borders. If I had said yes, I would have been able to scout his land, but I would have had to delay my invasion another ten turns.