Hi, I've been busy with final exams this week. Anyhow, what specifically do you need help with?

Awesome :)

Make sure you didn't apply any other bones to it. You can apply more than 1 bone to a model, so it might be that you accidentally assigned the hat to multiple bones.

I'm glad it worked.

Not sure how this is so difficult, but you need to do exactly what I said: FIRST join the two meshes into one object (you didn't do that according to your picture). SECOND select the combined model, then shift+select the bone rig and press "ctrl+p" > "with empty groups" to parent the model to the rig. Then follow the steps in this picture: http://i.imgur.com/EwMb03I.jpg

I think you got the first part working, but just in case you need an explanation: you need to parent the object to the bone rig before anything shows up in that list.

As for exporting as one model, you will need to combine both meshes into one object. Do this before assigning bones to anything (I think you can do it afterwards, but it's better practice to assign bones to everything once the model is more or less complete).

You can join objects by select both objects from object-mode and then pressing "ctrl+j" to join them. Now the model should be one object. Go into edit mode and rig the model as before. Then export the model when done.

Joining them into one model is what you want, but you'll still need to assign each individual bracer to a separate bone (or bones).

trgdy has the right idea. You can test this more simply by following these steps:
http://i.imgur.com/EwMb03I.jpg

I'm not sure... I'm fairly certain that the problem lies in the model and not the QC, and you might benefit from starting a fresh scene (with a new bone rig) and redoing the jigglebones. You could try reducing the tip_mass value to something like 100. Try that (it might be that the mass is so heavy that it drags it to the ground).

Well first of all jigglebones do not show up in the preview (unfortunately this is a bug on Valve's end). You'll have to test your model in the itemtest map or something.

As for the actual jigglebone itself, if it isn't being positioned properly, chances are it isn't your QC. It's probably how you set up the bone in Blender. I would take a look at this video https://www.youtube.com/watch?v=JP9ce_ygeSA

Yeah buddy, no problem. Good luck getting everything to work. Sometimes I wish I had more free time to just mess around and make more tutorials, but alas... I am just a medical student :P