To OP, "A: Maehiro: To be absolutely clear, there is no direct connection between FFXIV’s Hydaelyn and FFXII’s Ivalice or even FFXI’s Vana’diel. They are not the same world in different dimensions or time—they are their own separate worlds. However, there are certain connections to people or objects that appear in these other worlds that figure into the story of FFXIV as it has been conceived and is being told."

The fact is a lot of the dev that work on FFXIV also worked on FFXI and FFXII. Hate to burst your bubble but that's the real answer to your question. That doesn't mean creature or elements from those game won't creep into Eorzea but you won't be able to go to Ivalice or Vana'diel.