It seems to me that everything you've said is logical, sensible, and overall is a good project plan for creating a fair, reliable system.
Now convince my mom the same thing. She knows how to use AOL, Windows, and IE, but she'd be hard-pressed to make a subdirectory and move files into it. She's certainly heard of Open Source, but she probably has no idea what it is. I'm sure she has no love for Microsoft, but when push comes to shove, my guess is she'd trust the Big Business types over the hackers whom the mainstream media has largely denigrated as a bunch of anarchists. Even though logically, the open system is much more secure, my guess is she'd still trust the Big Boys over the FSF people. As for Stallman, I would say he's unquestionably brilliant, but again, my guess is my mom would trust evil Bill Gates (irrationally or not) over RMS.
It seems to me that in order for this system to really take off, you've got to "sell" it to people that have *no idea* what you're talking about. Call them the sheep, the uninformed masses... I call them mom... but you have to convince at least some of them to call their congressmen and say "I want this system, because it produces fair and just elections".
I'm not exactly sure how you'd do that, but one way that comes to mind is to get IBM, Compaq, and other companies that like open source products on board, even simply in name only. My mom certainly knows who IBM and Compaq are, and my guess is she'd trust them with technology issues more so than RMS and the FSF alone.
Clearly you've hit on an important issue here; Microsoft (for example) would certainly have an "interest" in keeping the source code of such a system closed... but Microsoft would argue that the FSF folks are a bunch of anarchist hackers that spend their time looking through mom's credit card purchases online, and can't be trusted.
A voting system is going to transcend a number of lines that not even computers have transcended. I seem to recall that something like 55% of households in america have computers (and I would guess it's lower in most other countries)... that's 45% of households in america that for whatever reason don't even have computers, let alone know the real (non-biased) differences between FS and closed source.
You've responded to a large number of the technical issues of how to go about creating a fair, just electronic voting system. Now you have to jump through the PR hoops, which it seems to me are flaming, moving, and have nasty spikes below them... a much bigger challenge than the technology hoops.
I'll continue to do my best to educate the moms of this world on these issues, but in order for this to really work, it seems to me some MAJOR muscle needs to be brought in...
Best of luck.