Exactly what I said. The element only determines what mods you can apply to the armor. It has absolutely no effect on the functionality of the armor. You could get arc and solar versions that would work exactly the same, you would just have a different set of mods you could put on them. That's all the element on a piece of armor means. It does not mean you have to use that armor with a subclass of that element. For example, since yours are void, you could put on a hand cannon scavenger mod, because that's a void mod, but you could [i]not [/i]use a machine gun scavenger mod, because that's an arc mod. If you go into your collection, and to the Mods section, if you look at the different armor mods sections, there are mods that have either blue, orange, or purple on them to indicate the element of that mod, and those mods can only be put on a piece of armor with that same element.

Yes. If you're running an arc subclass, there is no need to have all (or any) arc armor. Instead, look at what mods can potentially be put on armor of different element types, and then choose armor pieces with elements that will take mods that suit your playstyle.

You can mix elements with any armor. Everything I've told you applies to all armor, not just exotics.