Market or such
Yes outfits can be used on all characters. Be aware that many of them have a different appearance on male and female characters (and female charr and asura often use the male versions), and some have different appearances on different races too. So if you want it for a particular character check how it looks on them first.
You put them on and take them off using the outfits tab on the Hero panel (press H, select outfits, if you’re already in a different tab you’ll have to go back to the main list first).
You can switch between your armor and all the outfits you have unlocked at any time without any type of cost (unlike switching armor skins, which costs transmutation charges).
Danielle Aurorel, Dear Dragon We Got Your Cookies [Nom], Desolation (EU).
“Life’s a journey, not a destination.”
“Life’s a journey, not a destination.”