When you add new servers i think it would be wise to have a system in place on the current full servers so that any players wanting to join up on these servers like Moogle for example would have to get an invite from someone already on that server. Be it from a guildy or a friend. This is to allow guilds that formed pre-launch to get all their players and friends to be with friends.
new players however should only be permitted to create characters on the new servers.
Players will always try to flock to the most packed servers this is guaranteed, dont let it happen.
Opening up transfers be them paid or free wouldnt hurt either