Just to confirm, owning two accounts is perfectly fine. Just remember that you will lose all progress you have made - it will be a truly new account.

If you are logged in on your "old" PSN Account that was originally linked, and you bought FFXIV on it or registered it to it, you should see the game available for download in your PlayStation Store library. Worth a check! If you installed the game from a physical medium (BluRay retail version of the game), try reinstalling it from that while having that account active.

I'm sorry, I'm not 100% sure from the top of my head and as it's past business hours in Europe right now I can't check on this. With gamescom coming up next week I probably won't be able to answer this - could I ask you to get in touch with our customer support to get a definitive answer to this?

EU: http://support.eu.square-enix.com/main.php?id=5383&la=2

North America: http://support.na.square-enix.com/main.php?id=5382&la=1