How cosmetics work?

I'm new to the game and I'm a big fan of cosmeticsm, so I have some questions about them.

They are like a one time use on one character? Or can I move these cosmetic items and share them between my characters? They are permanent to my account?

Hi there,

The overwhelming majority of MTX are not consumables - you unlock them on your account and it's then free to use them or remove them from each of your characters at will. Unless you pay for duplicate MTX, you can only use them on a single character at a time.

The only consumables I can think of are fireworks and skin transfers. You buy each of those in groups, so it should be pretty obvious they can only be used once each. Skin transfers are used to take the appearance of one of your items and apply it to another. The weapon skins and armour skins sold in the store can all be used as many times as you like.

Almost all cosmetics (and other mtx) are permanent and can be moved around at will. The couple that can't say so, and they're the ones that come in big stacks rather than buying one at a time.

(Edit: oh man too slow)

So, if I buy an Armour Set, every single armour gear that I equip in my character will have that appearence? Or I will have to keep transfering that appearence to each new gear piece?

You used to have to keep transferring it, however GGG recently replaced the MTX system and now we've a Cosmetic tab in the inventory. You "equip" MTX in slots just like regular gear.