Multiple designs in one Photoshop mockup

I’m trying to use this mockup to showcase 3 different designs on 3 boxes. I found this mockup that has 3 boxes and within the PS file you can see it’s broken up into Left box, Right box, Top box. But when I go into the Left box ‘front side’ smart object to add my design, it does it across all front panels. How can I edit just the panels for each box?

How to have multiple layers of an embedded smart object?

I have used photoshop templates where you place an image in a embedded smart object, save and then the changes are applied in the file. The image placed in the embedded smart object has multiple layers of the same design amongst different groups in the templates I have used. How is this possible? do you just duplicate the layer and each one is update when altering the separate embedded file?

‘Un-smart’ object in Photoshop

I’ve created a design in Photoshop CS6, and used a large number of smarts object which made the workflow more easy (at least for me). Now I’ve finished working on the design, and I want to “unsmart” all the objects due to the large file size of the PSD. I do not want to do Rasterize Layer because I want to keep every layer which was originally on the Smart Object.
I want to convert each smart object (some of them have Layer Styles applied) to a group (folder) which will have all the layers inside + the FX applied originally to the Smart Object and it will be in the exact location of where the smart object was before.