Free 30 days only apply for base game. Expansions doesn't include free 30 days, pre-order or not.

When in doubt, check the developer/publisher site. Nothing in SE store hint at 30 days free for SB, at least not that I found (but then again I'm severely lacking sleep, might miss it). Maybe heavyarms is bullshittin', or maybe they include a time card to promote sales. Or maybe I'm an idiot (very high possibility).

Either way, if you already have base and heavensward, there's no sense in purchasing a complete edition, right?

Nope, there's two edition for complete, standard complete and collector's edition complete.

No, complete edition is slated for sale after SB launches. Even if you pre-order now from stores, you won't get it until after the store is allowed to ship them out. So early access is definitely a no.

You're just in free trial (which I guess to mean that you haven't bought it), so I suggest cancel it and make an account on the EU version. All version can play in any language they have and any servers with anyone, but if you check the newbie handbook thread, it shows that paying in GBP (euro version) is cheaper than paying in USD. And from experience, when I had my NA account, they won't accept my RHB debit card, but the eu version does, which makes it easier to subscribe.

For NA, I had to use paypal (paypal conversion cost and paypal tax) to buy ultimapay (or whatever it is called), and use that to buy crysta, and use crysta to top up my subscription. Total cost? 65 ringgit. 65 ringgit back before our beloved Jibby sank ringgit value. It will probably cost more now with the same method (there's probably a different way now, but still, usd is expensive). For EU in may 2017, paying in GBP, direct to square enix because eu version accept RHB debit, 43-44 ringgit.

So.. Yeah, if you haven't buy the NA game, don't. Go make EU version. Your progress in trial account does not worth extra 20 ringgit every month. Trust me on that, I went broke last time I played using NA version