Questions about skins

Hello everyone! I’m new here and in forums and I’ve only played this game singleplayer, sorry for my complete ignorance, I was curious about skins, those you buy, so here we go:

Are those skins available in the editor to create custom maps and campaigns if you buy them or are only available for multiplayer?

Do you need to buy them all? isn’t there a way to get them another way?

Again, I only play singleplayer and I’m not interested in multiplayer at all, but i would love to use skins in custom maps and campaigns, or even the official campaign, thanks in advance to anyone answering

You cant use the skins for sc2 editor, but if u equip them, they´re applied to the corresponding unit. Regardless of wheter the map has changes (except the look) of the unit.