That is a good idea. All of it, I think. I mean, if needs some thought, but it could turn out to be a solution to this problem.
I think though that, for the arguments, a low star rating shouldn't count as much as a high star rating or grade. It shouldn't effect your overall score. When you get a five, it's a heavy agreement. When you get a one, though, it's a heavy disagreement. Now, where there is information at all, there has to be SOME sort of credible information, right? Usually, as I've come to notice a lot, when there is a heavy disagreement, it's not that the person's opinion is SO wrong...
Or, I guess what I mean is, if you're giving someone a 1 star, then that means you cannot find ANYTHING useful in the argument. Even in Joe's arguments, the ones that are maybe supposed to be funny, I know that I would at least give a 2 or leave it alone... not a one though... One stars are extremely biased... and I cannot find a way to explain it just yet, but maybe you understand what I'm getting at. A five star is just a "I completely agree" or "That's a damn good argument. Five stars should weigh more than one.
On the debate topics though, I sort of see this getting played the same way as the arguments are being played now. There are expectations that should be met when creating a debate. First of all, is it really a debate? Is it something that can be argued? Those sorts of things.
Maybe, the down votes in general shouldn't weigh as much as an up vote. Say, a down vote is worth, 1/5th of an up vote. That way it would take 10 down votes to drop someone 2 votes, as they are now. Will there be 10 trolls voting each of your arguments down once x400? lol, I doubt it. At that point it would become a completely different problem. Someone's who is intentionally trying to corrupt CreateDebate in general would be responsible for something like that, and it would be clearly identifiable by anyone who has the ability to look into the issue.