Not sure of how much help I can be; I've never cosplayed, but I do sew (and help my friend off and on on a costume of hers every now and then).
Fabric-wise, I like your choice on the silk-type fabric. I would suggest that you get it in the dark blue instead of the light blue, and use fabric paint for the light blue parts (just do a test run first, though; I've never used fabric paint on silk). The gold parts, however, would definitely work better as a separate cloth sewed over top. As just an observation, the blues seem to be a thin material (like your silk) but the golds seem thicker (the back-flaps and the top). I'd almost say like that cheap, thin leather you find at Michael's craft store.
I give a thumbs up on the strapless bra as a base idea, but also suggest that, if you find it doesn't work, perhaps try a bathingsuit/bikini top and alter it.
On the other side of the coin, I say thumbs down to the cardboard in the bow idea. I know I don't know you, but if you use cardboard, I'd be inclined to go over there and smack you with it. Sew wires into the fabric, and use those to shape the bow. Or even those plastic ribs you find in corsets/bodices would work better. I'd say that the only time you can use cardboard for a bow without it looking tacky is in closed-type bows, like sometimes found on the backs of kimonos (the kind of box-shaped ones). However, the hair bow could probably use small amounts of cardboard, and get away with it. But, I must avidly protest against using it on the back bow. I've seen bad cosplayers, and, again, I don't know you, but I don't want you to be one of them.
Not really sure on the arm/leg bracers; the only thing I can suggest is, since the arm bands look like a type of jewelry instead of cloth, perhaps pvc pipe? I know lots of people use it for weapons and armor, so the clunky jewelry would be about the same.
Now, for a list of other things you didn't mention, but I feel like throwing in anyway. Shoes: best bet (I think) would be to buy ones that have the correct ankle wrap, and then add on the toe covering (either thick fabric with supports, or even pvc pipe...probably with fabric over it). That weird gold thing towards the back of the waist band (and just in front of the back-flap): pvc pipe (it really has many uses), styrofoam (with some sort of sealent or something over it to hide those air pocket things), or even a type of wire mesh or chicken wire with something over it. Necklace: would probably work best as pvc pipe; otherwise, probably the mesh wire. Hammer: either whole thing out of pvc (in true weapon fashion) or, to get that texture on the hammer head, I'd suggest using two flat pieces of some kind of hard plastic for each end, using some kind of curved support beams to flesh out the shape, and using paper mache (as tacky as that sounds) to get that bumpy texture, and then use some kind of smooth surface material to make the white designs. The shape of the back-flap: use a wire frame inside the fabric (best example would be to google fairy wings, and look at how they make the nylon ones that they stretch over a wire frame). Oh, and make sure you get a wig; more often than not, using your own hair turns out worse then using a wig.
Yeah, a lot of talk from a non-cosplayer, but I hope it helped in some way. (Meru's my favorite character, and I want cosplays of her
). If nothing else, you can always try and google specific tutorials for cosplay (i.e. big bows, arm bands, etc). Good luck!
I was a bit a afraid it might have been information overload (I have a tendency to prattle), but it's good to know you understood my gibberish 