I don't think Shiva's FFXIV art looks anything like her FFXI counterpart. But Ramuh certainly does resemble his FFXI equivalent. And I can't remember where I saw it mentioned, but it was generally regarded that Atomos in 1.0 was the actual Atomos from FFXI, as it crosses dimensions after all.

As for Coerthas and San d'Oria, I think you're getting mixed up with Ishgard which is the actual nation - Coerthas is simply the highland area that surrounds Ishgard and forms it's outer territory. And Ishgard is also different from San d'Oria in that the later was an actual kingdom with an autocratic king as it's head of state, where as Ishgard is a literal theocracy ruled by a bishop.

For real-world equivalents, San d'Oria is much like England in medieval times where as Ishgard is more like Vatican City - two totally different systems of government (the only nation in Eorzea that was mentioned as being like San d'Oria was Ala Mhigo before the Empire invaded, as that was a theocratic monarchy as well - they even had an order of religious monks in their army called the Fists of Rhalgr.)