New player, need things answered.
yes
Ok. The Toxic Mantle Skin is armor. You can put it on one item immediately. If you want to use it after on another one, you need either Transformation Stones (up to lvl 79) or Transformation Crystals (lvl 80). Once used it is souldbound to the character.
Mad King Outfit is Town clothing. It cannot be worn to battle. You get just one copy of it, but it is account bound so you can take turns on what character has it.
If you purchase a skin like the Toxic Mantle skin, you can apply it to one piece of armor. You can then use Transmutation Stones or Crystals to transfer that look to other pieces of armor as you level or change your stats.
Costumes are account bound. They are town clothes only which just means you cannot wear them while you are in combat. If you are wearing them in the open world and a mob hits you, the game will automatically equip your combat/stat gear.
Since Costumes are account bound even after you equip them, you can put them in your bank for your other characters to use. When you equip them you can toggle the town clothes look on and off on your Hero panel but they can only be used on one character at a time.
Any skin items are usable once. After that it is bound to the item. You can, though, transfer the skin onward using either a transmutation stone (gear lvl 1-79) or a transmutation crystal (lvl 80 gear). Those let you take 2 of the same items, and pick the stats, the skin, and the rune from either item.
A slight addition for completion on skins, Hall of Monument skins (from playing gw1) and Zanshin/Radiant/Hellfire skins (from getting enough AP in gw2) are also 1 time use, but you can get as many copies of the skin as you like.
For costumes (town clothes), those are permanent (but you only get 1 copy of them). You can turn them off/on at will, but you can not fight in them, and combat will put you back into your normal armor. Most town clothes are to either look different when not in combat or to play costume brawl (and let others play as well).
Skins: An armor skin is transmutable onto any like piece, i.e. any medium glove skin is usable on any other glove skin, with a few exceptions (should tell you in the description.) The gem store skins you mentioned are class independent, so you can use the toxic mantle on any shoulder piece regardless of heavy, medium or light. Once you use a skin you can in turn use that piece to transmute another of the same type, unless it is a one-time use skin, which again, it will tell you in the description.
Townclothes and costumes: These are usually whole outfits that replace the town clothing slots. They are not armor, and you will be bereft of benefits should you use them in battle. There is a toggle in your hero panel that switches between town clothing and armor. Unfortunately, you can’t transmute them onto armor. This is sad, because many times the town clothes look better than the armor, (i.e. I would kill to be able to use the Bloody Prince outfit as armor skins. ) I almost never wear townclothes, even in town, so I will probably never buy them.
Hope this helps.
Level 80 Elementalist
yes
Why even bother posting this? It doesn’t even begin to answer his questions accurately and serves no real purpose.
To OP: Make sure you read the tool tips of everything in the cash shop, and it will identify it as a skin or a costume / town clothes. the differences between those two have already been explains.
With skins, you can essentially ‘re-use’ them infinitely as long as you continue to use a tansmutation stone or crystal, depending on your level.
Wow, this! I’m honestly surprised how many people and how fast it was answered. I am grateful. Thank you all. ^^