(1) and (3): I really cant understand any concept that forces you to "endure" certain certain historical events instead of letting you control them. If you want to replay history, why dont you read a history book instead? I personally like to try it my way.
Btw, what if I respectively name my cities after the holy cities of religions? And lets say I also make sure the "real" cities wont exist when the religon is about to be founded? Or even if I dont raze them, I might be lucky and get the religion?
This also shows my main problem with historical events. Since you are very well aware of them, you are effectively seeing the future.
I also like this idea, but only if there would be fictive civilizations, religions and wonders. Mixing alternate history with real history is not very good thing
But the fact that as the incas you can conquer the world is quite the mixing of history and fiction. Following your logic, this should be prohibited too, and ultimately the game would just play by itself.
To be historically correct.
(2) I see your point with this one, even if I find your reasoning with combat system a bit strange. The flaws of one-on-one combat is covered by the aid promotions pretty well IMO, and since that IS the combat system of civ games, its rather pointless to reason with it. Youre talking about army sizes, but if you look at history, a few thousand defenders in a good fortification repelled more than hundred-thousand men armies countless times. Of course the attacking armies werent destroyed either.
I would suggest you to try and resolve your problem with unfairly strong defenders by adding high retreat odds to all units. Would be a lot more realistic, even if it would make defensive wars a real nuisance.
Btw, I like using small but high-quality armies, instead of large numbers, so this concept surely doesnt fit my playing style. I never find any real problem capturing enemy cities, even if it takes 10+ turns of "siege". Its not only about building a big army and throwing it on the enemy, even the AI does better than that.