Personally I'm more optimistic than
@jorissimo, maybe a 19-city Justinian would be a threat at Immortal, but I doubt so at Noble. He's also not one of the AIs that goes for cultural victories (he might but only if he owns multiple holy cities). Just send some scouting units around his land, check the red fist and if he looks like he's invading upgrade your own defenders to the modern units like Infantry / Machine Gun / etc. No need if he's not invading though.
A couple questions now that I'm out of war:
- I'm building universities so I can build Oxford. Is that the play right now, since I can whip them?
Yes, that's correct. Oxford goes in your bureaucracy capital. Do you have enough hammers there to build stuff without whipping the population away from your towns?
Also, you seem to have a lot of excess happiness in your cities, maybe you don't need hereditary rule anymore? Representation would generate a lot of research if you have e.g. coastal cities with much excess food but not a lot of space for workshops, they can run Representation-boosted scientists. You could change to it later at the same time as Caste System. That said you will need the excess happiness whenever the AI start switching to Emancipation (they need democracy for that), you want to stay in Caste System and not switch despite the unhappiness. So maybe keep Hereditary Rule then.
Another option is to run Representation / Caste System / Pacifism during a GA if you can generate some great people in your best food cities, and then switch back to HRule and Free Religion (but keep Caste) at the end of the GA. See below for GA timing.
- I've unlocked factories and such, should I build them right now? They're kind of expensive
They're only for your production cities. A good workshop city should easily to around 40 base hammers, with a forge that's 50, that would create the factory in 5 turns. If you don't have transformed all your land yet (any flat tiles that are not towns), build more workers. Be careful of the massive unhealthiness that it will generate after you build a coal plant. In the city risks starving from unhealthiness, build some health buildings (Grocer/Aqueduct/Harbor) before the coal plant.
- When should I do a golden age? I've saved the great spy I've had from Communism until now.
You can save it for when you want to switch to Caste System and when most of your cities are working all their good tiles (almost everything is covered in either towns or workshops/watermills). The way GAs work is a bonus for every commerce and production tile, so the most tiles you're working the highest benefit you get.