New player about to buy

Hi everyone, I'm a new player that just got to the max level for the trial. I'm on the Lamia server. I was just wondering if there's anything I should know about buying the game. I played the trial not on steam, so I want to make sure my account can be played from there (I'm sure it can), and that steam is the cheapest option.
Also wondering if there's any companies I should join on Lamia while I'm leveling up, so far the game is pretty understandable but, that brings me to my real question-

Is there anything I missed by playing the trial version that will confuse me once I buy the full game? I'm not supposed to have a chocobo yet am I?

You usually get your Chocobo around level 20 for joining a Grand Company and farming 2000 company seals. Whether or not Steam is the cheapest option and allows you to play with your non-Steam trial account, I really don't know, but I'd assume so.

Also, if you let me be your referrer, I'll love you forever.

Sure! Not sure how to send messages, but send me the code! I won't buy time until mine is up, though!

The code should be WQTTP4US , thanks a lot! And no rush with the buying! Though I believe codes only work for 2 weeks after getting them or so, but I'd happily give you a new one if this one expires.
If you ever make an alt on Cactuar, feel free to let me know and I'll support you a bit.

The code is good for 120 days. Your characters are saved server side with your account and everything will transfer over when you buy the full game. Where you buy from doesn't matter. The clients are the same. If getting the game on stream is cheapest then you should buy it there and not worry about losing your characters.