So, there are 3 items you're getting mixed up, lets separate them:

3 days Early Access (24th-26th)
14 day "welcome back campaign"
30 day subscription for registering ARR

Right now as a 1.0 account, you qualify for the 14 day welcome back.

If you were to pre-order any version of ARR, you could use the code to gain early access.

If you purchase a PC version of the game, you CANNOT add it to your current account, there can be only 1 FFXIV PC account on a given Square Enix service account. The solution to this would be to purchase the PS3 version of the game. If you purchase it from a retail store, you will receive a Preorder code which you can actually redeem for PC early access (people on the forums have done this). If you purchase it from the PSN network directly, you will not be given a Preorder code, but simply have the PS3 early access added to your account.

So to summarize, if you preordered:
The PC version, you'd get Early Access, and 14 days free
The PS3 version, you'd get Early Access, 14 days free, THEN ANOTHER 30 days free.