There are two types of Mitzvoth (commandments), 'Aseh and Lo Ta'aseh (positive and negative; ie., "Thou Shalt" and "Thou Shalt Not").
a. Positive commandments, with some exceptions can be enforced with certain types of rabbinic sanctions but no actual punishments, whereas
b. negative commandments carry with them specific forms of punishments, delineated in the Torah or derived therefrom.
There are also at least two types of Tzeni'uth (modesty), related to dress and to action*. Within those there are also forms of modesty relating to
a. how sexually/revealingly one may dress or how sexually provocatively one may act, as well as (and seemingly separate from)
b. the idea of not drawing too much attention to oneself generally, whether with outlandish clothing (that is not sexually revealing) or with outlandish behavior (that is not sexual in nature).
Question(s): Are all the laws of Tzeni'uth part of the same Mitzvah (or set of Mitzvoth)? Do they all stem from "Kedoshim Tihyu" ("Be 'holy'")? If it's all part of the same Mitzvah or set of Mitzvoth, is it positive or negative?
Bonus: if the different forms of modesty are all ultimately connected to 'Arayoth (dancing in the street in a neon green jumpsuit may somehow attract a sexual mate), does modesty apply to non-Jews, who, per the Shiv'ah Mitzvoth Bnei Noah (the 7 Noahide Laws), are prohibited from committing many, if not all, of the forms of sexual deviations that Jews are prohibited from committing?
*For purposes of this discussion I am including speech in the category of action.
Fascinating discussion on the subject of hair covering, which expanded to Negi'ah and other areas of Tzeni'uth, and ultimately devolved into "AHHH, WHY ARE WE EVEN DISCUSSING THIS?? Why not just permit EVERYTHING!?" here: http://www.theyeshivaworld.com/coffeeroom/topic/covering-hair-once-married