Would I need to create a copy/sub folder for editing purposes?
No. (you could, but it is not necessary). Adobe ACR edits JPG and TIF (as well as raw NEF). It is lossless edits, which means it saves (in the original file, but elsewhere in it, like Exif is stored elsewhere in it) a list of the changes. It does not change the image data then, does not actually implement the changes (except in the monitor temp copy you see), The file is always still the original image, but it simply saves the list of changes. Other programs viewing the original don't know about that, and they still only see the original data. So then when ready, in ACR, you output a new JPG for other uses (which implements the change list only then). And when you later decide it needs additional edit, subsequent edits simply change the edit (to update the change list automatically), and you discard the first temp output, and output a new one to be used as the edited JPG.
You can change your file associations to cause clicking a JPG to open ACR automatically, but nothing is required to simply open a JPG in ACR. You just "open in Raw" in the normal way (even if it is JPG).
I shoot only Raw, but I edit all my wife's little compact JPG in ACR. She thinks it takes wonderful pictures.
The ACR tools are simply better and easier, more to the point for editing photos.
For me if I were using .jpg, I would save under a different name to keep the original from being affected. That is using any software.
It is good to have the original, for whatever the future holds. But going back to a saved copy means that you have to start all over on your editing efforts.
If you do lossless edits with ACR, you simply update the change list, maybe make the image brighter, but do not have to change the white balance and contrast again, unless you want to. You are editing the edit list, and keeping what you want of it. You never see any list, you just re-edit the image as desired. At any output, that edited change list starts with the original image again. This is a very desirable whole new world.
Just to make it clear, maybe silly, but hopefully clear. Let's say we want to make our image be very blue, too blue, but that's what we think we want. So we do.
Next week, we decide that was wrong, it's too blue, and what we really want is too red. So we change the edit to make it be very red. We keep the rest of it, the crop, and the brightness, whatever. We just make it red now.
Lossless edits means it does NOT have to undo the blue in the data. It is still the original data. It simply changes the blue instruction in the list to be a red instruction. The data is NOT shifted back and forth, it will be changed only one time at final output. This is good stuff.
Raw images do this by default, i.e., ACR is required. A serious part of their advantage.