OK, First off, Sitters hasn't checked in here in some time - I don't know when/if he will again, but just about everything he offered for this game is in the Data Source folder in the SVN (which is not part of the trunk, if you've downloaded and compiled the game from SVN or grabbed a beta installer you would not have these files, as they are in a separate folder). Fortunately the data source is publicly accessible, you can download it from SVN separately from the actual game or go to the sourceforge page and use the web SVN browser with your standard Internet browser, no special software required.
In the data source you can find all kinds of models and other files for stuff that was offered for the game.
As for the human models, I'm working on heads for soldiers, and later on possibly new ones for other personnel and civilians (The civilians could use a futuristic look, but I'm not going to even consider starting on those at this time).
If you're working on email pictures I would suggest basing them off of the approved modeled heads for the various characters, although Winter's the one who could really answer that.
Actually, I'd bring up all of these points with Winter - He would really be able to give better answers to all of these issues, as well as the fact that he's in charge of this stuff.
I hope that helps.
P.S. - If Winter accidentally misses your questions in this thread I'd suggest sending him a PM.