I am just as hungry for these details as you are, believe me. My closest understanding and belief is your top Option 1, except that I am not so sure servers will be renamed. I do believe (hope) our 1.0 chars will be dropped onto the server they were on before, with a future option to transfer if desired. I also believe that all 10 original servers will remain JP region and only new servers will be other regions. I believe this because I don't think that they will shock JP players by having them log into their character and suddenly be on a NA/EU server.

A post was made by a dev at some point (maybe someone can find it) where they said that they don't know the answers yet and are depending on information gleaned in Beta (to see how many players return, etc.) in order to iron out the details.