Getting an exotic armor with different prefixes

Cultural armor is indeed different for each race. The differences aren't just cosmetic, as each race's set of armor has different set bonuses.

Race        Major Bonus     Minor Bonus 1     Minor Bonus 2
Asura    Condition Damage     Vitality           Power
Charr          Power        Critical Damage    Precision
Human          Power          Precision      Condition Damage
Norn           Power          Vitality         Toughness
Sylvari  Condition Damage     Precision        Toughness

The armor is roughly analogous to Prestige Armor from Guild Wars 1, though that armor was entirely cosmetic. Because of its higher cost, it's a way to reward players who have had the time/resources/money to acquire that much gold to afford the items.

As of this moment, because it's so early in release and the Trading Post is still disabled, it's difficult to know exactly how this armor compares, stats-wise, to the crafted Legendary sets in the game, though it is almost certainly better than the random mob drops.

TL;DR - You can't change order.

Before and shortly after game release there was rumors that you can change your order becouse of old Wiki page about Order that sayed that player "would be able to change Order with a little bit of effort".

It was written in disscusion on this page this information was mistake and "choice seems to be tied into game mechanics".

Source of this missunterstanding is quotation from Ree Soesbee, GW2 Game Designer who was missunderstanded as she said;

The choice of an order is not compulsory, however, you can’t progress through the full extent of the storyline unless you do so. You can change orders once you’ve chosen one – with a little effort – but parts of the storyline are linked to the orders, so in order to see certain facets of the personal story, you will need to join one. That said, you can play the game without joining one if you truly choose to do so.

But true undesrtanding of this statement was explained few posts later;

You can get through the all major areas in game, but not through the whole story. You can do dungeons/events level up and visit every part of the world - except your personal story will stop progressing.

And;

So I could play 99% through the story (but not finish it) with order A, then switch to order B, and do 99% of its story, and then order C?

You won't be able to do that.