Vos and vosotros aren't the same thing. Vos is in place of "tú" in Argentina...it's what I'd use automatically, but I recognize that "quieres" is what most people would. Sorry for not using the accent, I just didn't think it was relevant since Duo doesn't teach voseo.
And honestly "queres" and "querés" would sound almost the same when spoken.
No, it's not specific to Argentina. We use it here in Guatemala. A man talking to another man will always use "vos" unless he uses "usted." Women typically use "tu" with one another and with men (and men with women) unless they use "usted." (However, sometime between siblings females will use "vos.") If a man uses "tu" with another man, it is typically assumed that they are gay.
And considering that Argentina and Guatemala are the two ends of Latin America (except for Mexico), I'd imagine that it is used everywhere in between.