Sometimes blender has this glitch. Try making a new blank black image (try going into and out of edit mode and removing any materials). Re-do the bake afterwards.

Eh... Looks like there is something wrong with the bake: Make sure to recalculate all your normals before baking (this might be why part of your model is black). To do this, select all your vertices in edit mode and press "ctrl+n".

Also, try not to break up the model into so many parts unless it is completely necessary. Always try to unwrap things using the smallest amount of pieces necessary.

It's almost never used... It basically tries to automate the process, and most of the time it just gives a bunch of seperated parts that will look absolutely shitty if you try to texture it. Just use a combination of seams and projection unwrapping which is what every professional modeler does.

I don't know exactly how I would ho about doing this other than using facial flexes. I think there is a similar item in-game that you could probably decompile and check out. Perhaps you could ask Napy.

The hat and glasses probably are just modeled regularly (probably using the bip_head bone and some other bone-- check a decompile glasses model).

The chin strap might use facial flexes, but then again I don't know. Did you look at Napy's guide?

Also, make this entire thing one model is a BAD idea. This is because there are many slots in-game (i.e. hats, glasses, beards, etc.). So if this was just one model, it wouldn't work because it would need to fill one of those slots, and you'd be able to wear two glasses at the same time. Definitely make a hat seperate from the goggles.

Awesome. Just don't forget about adding in hard edges (edgesplits) or "smoothing groups" as they are known in other programs. https://dl.dropboxusercontent.com/u/10100459/BlenderImages/edgesplit_690.jpg

Don't put it in the usermod folder. Put it in the C:\Program Files\Steam\SteamApps\common\SourceFilmmaker\game\tf\ folder. Make sure that your folder structure matches exactly how it is in the Team Fortress 2 folder (otherwise the engine won't be able to find the .vmt file).

Yeah, stick to quads unless you're dealing with faces that are just triangular by nature (i.e. if you are manually editing certain parts of a model).

To join to meshes, select both parts in object mode and press "ctrl+j".

The handle looks fine to me. Unless you want exactly straight UVs... which is not really necessary. I mean you could manually align all the vertices, but this would be a futile attempt. Also, did you triangulate your model after you unwrapped? There is no reason to work with tris in blender (just use quads). Exporting to .smd format will automatically triangulate your model.

Lastly, the way you projection unwrapped the head piece will give you weird black seams because of the way you unwrapped it. I would never unwrap it like that. Do it similar to this:

http://i.imgur.com/5XBHa3e.png

Something like what?