First Spoiler - 4000 BC to 850 BC
Just a really quick post; it's already the 26th so time is really short this month.
I entered the MidAges in 1100 BC, and finally contacted Persia in 850 BC to qualify for the first spoiler. I needed about 8 turns to learn Republic, so the plan was learn Republic, revolt, upgrade a bunch of Warriors to MedInf then have at it with the Indians. So became a Republic (5 turn Anarchy) somewhere in the 500's BC, and once a Fur deal with the Indians expired, declared on them and moved the MedInf forward.
Lots of mistakes in this. I'd just recently obtained 3 more Luxuries through Tech trades; 2 from Persia (which was far behind) and 1 from Carthage. Declaring War cut our trade path, so I was now down 3 Luxuries (4 if you count the Fur trade I didn't renew with India); I'm sure this has trashed my reputation as well.
2nd mistake: with MedInf and large culture difference probably best to just raze Indian cities, to rebuild with nice Byzantine ones later. I timed my DoW for when I had Feudalism but India did not; so I'm facing Spearmen and occasionally Horsemen or Swordsmen. I've brought a Pike and 2 Trebuchets along, so my MedInf should stand up pretty well. Keeping the Indian cities meant diluting my forces (to defend them) and risking the occasional CF (which did occur.)
So I brought my force to the edge of Delhi's culture, but was down to only 5 MedInf available to push forward, which I thought was pushing it a bit. We settled into a grinding give and take; I founded a city that put me one movement turn away from Delhi but couldn't quite push through. Meanwhile, a second force was going up the coast capturing cities while the Delhi force held fast. Then War Elephants started to show up. At that point I got a GL, and formed a MedInf army, which gave me some capability to counter the WE's. India built KT in a tundra town down South; I sent an expedition to capture that. Finally I got enough force together to push through and take Delhi - 8 MedInfs vs 3 Pikes and 3 Spears did it. 350 AD (a long time!!). Got Theology and Invention as part of Peace along with a couple of India's outlying cities.
Research was essentially turned off during this time; I was waaaaaay behind, time to play catch up. The Ottoman, Carthage, Vikings and Russians were driving the research, and showed up as having Education, Chivalry and Gunpowder. So, going against form, I research Printing Press. My GA had started about 10 turns before when I finally had a chance at an Indian Galley, and I've built up a Treasury of around 2000 gold; 4 turns later I had PrintPress, and was able to get Gunpowder, and some gold and gpt, and one Luxury. Trading GunPowder, PrintPress and about 200 Gold got me Education from India. OK, the leaders have Banking, Astronomy and Chemistry as well; hmm, I'm still rather far behind. 390 AD.
Alright, I check and Carthage will sell me Astronomy for the least amount. I plan to do 3 of 4 turns research, then buy it to finish off. So in 420 AD, I buy Astronomy for about 300 Gold, then I manage to make trades to get Banking and Chemistry. I get a notice that Russia has started Newton's University; they are unique with Physics, and obviously have Theory of Gravity as well. I start on Physics. Metallurgy and Navigation are known by several, so I can start trading my WM for TM's or whatever Gold I can pick up.
Mid-400's, my GA ends, and that stupid Delhi flips on me.

I'd been rushing Settlers out of it (Size 11 when I captured it, with Oracle and MOM), and was setting up a Palace Jump, just two turns away!!

I have lots of units within their culture of course, but I'm not going to let him reinforce it so declare, and retake. Darn thing flips again 3 turns later, so this time I take it and raze it. My reputation is completely shot. So, in retrospect, Delhi flips, all the Northern coastal cities flip back before the end of the first War; I should have been razing and replacing all along. This time I get Persia and the Dutch to ally with me to help cement our relationships; they are rather far behind so the Techs I know are worthwhile to them.
Anyway I do about 5 turns of reseach on Physics; by this time it is known by 2 or 3 and the price is less than 100 Gold when I buy it - 470 AD. Russia is still exclusive on TofG, but no one knows Magnetism, so I start on it. Takes about 10 turns and Russia knows it before I finish (but wouldn't sell it for a reasonable price - wanted 350+ gold when I could do the last turn for < 200 research). I learn Magnetism and trade with Carthage for Metelurgy and the Ottomans (Mag and Metal for Tof G) to bring us all into the IA (570 AD). Russia and I got Nationalism, the Ottomans got Steam Power and wont trade it. I gift Persia up, and Xerxes gets Steam Power; now that it's diluted, he will trade it (ha ha, Osman!). Catherine lands a LongBow adjacent to Constantinople, and declares when I insist she withdraw it; she'd been itching for a fight for several turns and finally found an open space (without a Byzantine worker on it

) to land.
So I'm at war with India (Dutch and Persians allied with me), and Russia. I have Nationalism so I should be able to nullify the Indian WE's very quickly with drafted Riflemen; and Gandhi is rather far behind. I have trading possibilities to ally people with me against Russia (maybe Osman would like Nationalism, too?). And I know all Techs except MilTrad and Democracy (and Free Artistry too, I suppose; I don't think anyone knows Econ yet.) I see Ainwood's sick resource joke (ha ha). Plan to finish India (finally) and build up for a tumultuous IA. A very challenging game, and I can't say I'm comfortable yet.