Hi Troy, 

I mad my Goldie costume 8 years ago, so I'm going to do my best with the descriptions but my memory is a little fuzzy on some of the details, especially for my original pants (since they fell apart and are long gone). My sewing on this one was rather unsophisticated: I knew how to sew at the time, but I cared a lot less about doing things "properly" than having it look right. One one hand, it means my results should be easier to replicate, but on the other, it might be hard for me to describe exactly what I did. I did an example of some of the sewing things I talk about: used lots of contrasting colours to make it clear what I'm doing. On the finished costume, everything was black.
Let's start with the shirt - sewing it from scratch was far too intimidating, so I basically sewed a layer of black satin over top of a bustier I bought - it's an easy way to make sure that it's going to fit. I didn't worry too much about the shape of the satin, just made sure that it was wide enough to cover the base garment with enough to fold over on the edges (ie at the hooks on the back). The length needed to be at least twice as long as the finished top - all the extra fabric is what gets gathered up into the "ruched" look. I decided where each of the stitching lines should go and marked that on the fabric (probably pinned it to the top of the bustier to make sure things were even). Using a contrasting thread colour, I sewed a gathering stitch on each of those lines, then pulled up the fabric until the top was the desired length (for how to do a gathering stitch: http://www.instructables.com/id/how-to-gather-fabric/#step3  in this case you only need one row of stitching instead of the two shown in the tutorial). 
The next step did several things at once - prevented the gathers from sliding around, gave stability to the slippery fabric, and also gave the look of the top-stitched seams that Goldie has. I adjusted the gathering so that it was even, took strips of scrap fabric a couple inches wide (one per gathered line), and pinned the gathered satin to the scrap fabric backing. Then I sewed along the original gather line as well as about 1/4" to either side of it. Then it's just a matter of pulling out the gathering stitch (the blue one in my example) and removing the pins.
Now that my ruching was done, I finished the bottom edge by folding it under and sewing it (since it was longer at the bottom than the purchased piece was), as well as the edge that was along the "eye" side of the hook and eye closure on the back of the bustier. For the top edge and the "hook" side of the closure I just folded the satin over the edge and stitched it down by hand. The hooks were a pain, I had to do a lot of cutting in order to cover all the purple but still be able to use the hooks to close the top. As you cna see from the back side, I also hand-stitched the satin to the bustier along all those gather lines to make sure everything stayed put. I had to add a little elastic across the top edge at the bust since there's no base to sew it down to and the excess fabric there wanted to sag out a little.

And that's all there is to the top.
I originally did the pants similarly - I found a different black satin that was less shiny, got some black leggings, cut the satin extra long, gathered at the outside and inside seam lines (think like jeans) and then stitched that to the leggings. The pants looked OK, but were not comfortable and eventually the elastic in the leggings disintegrated and they were useless and got thrown out. I thought it would be OK using a non-stretch satin for tight pants because I was building it on top of a pair of stretchy pants, but despite planning as well as possible, it did not work. The pants I wore most recently with this costume were just cheap, thin, pleather leggings that I got from the mall. I'm planning to alter them to also be ruched because I love my accuracy, but for just hanging out at a comic shop, the pleather leggings were perfect. and SO MUCH EASIER. 
.... but I am a perfectionist, and if I ever do an actual photo shoot with my new leggings, I'm going to be altering them. I'm going to try doing it with elastic thread instead of gathering though since it seems like it will be easier. Basically, follow this tutorial, but apply to inside and outside pant seams instead of shirt side seams. http://www.thesewinggeek.com/add-ruched-side-seams-to-shirt-pattern/ I have an extra pair of the leggings to use for the extra length needed.

As for the duster/jacket... There's not much I can go into. I bought a simple long coat/jacket pattern and red silky fabric and pretty much just followed the pattern. The only really unique/weird thing about it is the collar/opening area. I ended up pretty much just adding a triangle-shape onto the edge on both sides.