I don't really understand it, why can't a growing city build chariots?
- right, got me here. Still, find it useful to produce samurai, maybe, too stereotypical, still cling to the idea that stuff is produced from hammers, not people

Seems like slavery cities will become our foremost army contributors, and best producers will be serving their needs.
MP has one drawback - it increases military upkeep. This would lessen with Vassalage, but marginal upkeep from extra units still'll be the same (though lower due to obsolescence factor to chariots).
Now to
Feudalism - we want it, and we want it NOW, i.e. before conquest. But now we can get it only from HC and MM, who require Astronomy. MM is willing to fight with Bismark as a free gift for shoppers, and it seems to me like a good way to stop him from building those nasty shipses. Otherwise we can trade MM Astro for war with HC (which will make MM adopt his own religion and tear him from Buddhist league) and trade Astro to HC for Feudalism. The question is -
are we better off with war among AI than without? Yes, I agree, they start building military, but once we start war, they will still do it - remember last SGOTM, when 100%-allied Arabs and Americans still had large armies, and here we have aggressive AI and a rising war-monger. If we make them fight among each other, this will slow their development down and open their backs for a stab as all their troops will be massed along frontline (attack Inca from sea). Consider this.