The adjustment layers are for creating the mattes and emphasizing different parts of the blend modes. The gold color is just a yellow or orange solid with a mask and an overlay blend mode.
If you want to get reflections you'll need to pick some footage or paint something, make it black and white then mask it to fit and use the multiply or screen blend mode to create the fake reflections. If you want to do something advanced like make your Midas actors face show up in a reflection you'll have to film the face, distort it so that the distortion matches the object that has turned gold, make tie footage black and white then use a blend mode to add it to the gold colored layer already put on top of the object in the scene.
If your camera is moving you have just added to the complexity because you are going to have to do some tracking, maybe camera tracking, maybe motion stabilizing and then adding the motion back into the scene so the "gold" stays stuck. If you have used a zoom lens you now have other problems pulling off the composite.
This kind of composite is created using multiple layers, blend modes, roto (masking) and opacity changes. A little color correction can also go a long way to making it work. There is no "effect" you can just apply and get the job done with one or two layers. I did a complex composite the other day that had 94 layers in a six-second comp by the time I was done. Almost every one of those layers used some kind of masking and a blend mode in addition to effects to pull off the composite. The master shot had 8 different objects that needed to be tracked and I needed to camera track the shot also to match some perspective. Just an actor walking down a sidewalk, but almost everything around him needed to be changed.