1) Not only the Iron Frigate, any late rennaissance/industrial/modern ship is ATAR (except for Ironclads). You're right, that should be mentioned. Problem is, 'Special Skills' like ATAR or movement boni for certain terrains are not autogenerated.
2)
You may be missing a basic strategy option that RandR offers
Wrong

. RaR
requires10% Lux. Reason is the missing 'marketplace effect' (luxury multiplier); instead, many improvements increase Luxury trade - but for this having any effects, a minimum Luxury rate is required. 10% Lux can make the difference between the capital rioting or on Wlt...whatever Day.
3) Slave Markets are ok. The Slave trade wonder can be problematic; consider almost any advanced Wonders increases the unhappiness from Slave Markets, and you cannot sell the Wonder. I'd rather hand-built a SM for 25sp, and sell it off when needed.
4) Rome: Problematic. Of course, this is a really bad city spot. But too many prerequisites would hurt the AI, since it can never cascade in that case. And, the AI will build everything that gives culture. A bigger problem for me are Opera Houses; we'll have a close look at them.
5) Finally someone who likes the Cossack

. Yes, it's one of my favorites as well. Great for xCC games, or domination where you require insane numbers of units, but quality isn't that crucial. ANd it's historically correct, considering Cossacks were semi-independent.
6) eric12345cn:
Sorry, I cannot help you here. You simply must have enabled Elimination. If the last game you started (like the Fall of Rome Conquest) had this settings, they are automatically carried over; you need to restore 'Default Rules' (as usual, without 'Respawn' and 'Culturally linked').
7) rea444:
Don't know what you could look for, Rhye's world map Mod perhaps?