I've seen many mods do this, they have one mesh that is used and different textures are applied on that mesh depending on the armor/clothing piece chosen in-game.

How do you do this? Is it a NifSkope thing? I've looked at the BSLightShaderProperties of these kinds of meshes and there seems to be only one mesh linked there (plus normal map).

Can these reskins have different armor values?

Can they have different armor types? eg Light Armor, Heavy Armor.

Can they have different crafting materials depending on the reskin?

Thanks.

CK has texture sets where you can define a new texture, you can have one mesh, make multiple duplicates of the items you want in CK pointing to the same mesh but swapping the textures for the texture sets you have made. Being duplicate items you can then make tweaks to get the differences your after.