I think I've seen them in all the photos but they're so light and small that they aren't seen. You're welcome to use my template if you like, this can be printed and then cut out of a sheet of plastic like from some packaging or whatnot. With some good theatrical black make-up applied with a makeup wedge it works well. http://www.mcapell3d.com/images/AsajjTats.pdf
After testing and trying several things what we opted for was to pull a little of the fabric together and run a thick round shoelace through it. I used a similar technique for the edges of the shirt on the front and arms to make the rim of the armour.
Yes, the belt should be like that reference is, in black.
Yes, the vambraces on that doll, like the boots, were design elements not seen anywhere else. We liked the look of the ones from the comic that Pam also has in the standards, but with that as a reference source they may be OK with Thomas, you'd need to check with him though.
Not sure. That is what I would try, but I would definitely test it out on a scrap of both the white and the dark fabric to see how it will affect it and get the timing down precisely.
Good luck with things. Happy baldcapping.