For question 1 I've read that they wanted XI player to feel familiar when playing XIV. They've stated that their primary audience was XI players then other players.

I'm guessing they didn't follow more aspect like XI because they're making XIV, not XI-2 or something, plus doing so would mean that XI will most likely be shut down. It was their goal to have both game running concurrently because there was even a 'deal' when you're paying for both game simultaneously.

Edit:
Also for number 4, expect a high and likely no. Erozea is not Vana'diel nor should it be.

I left XI for XIV because I wanted something new and fresh, for better or for worst, not more of the same.