I agree that there might be some issues with comment limits--you don't want to limit discussion too much.
On a different topic, why do you think this system should be anonymous? You can't limit votes unless you can authenticate someone's identity, and the best way to prove that users are real is to show who each user is.
Corruption is only possible when you know who to bribe. By making the system completely anonymous, bribery becomes extraordinarily difficult, if not impossible.
Further, all ideas should receive equal consideration. Attaching names allows for group-think and bribery. (Imagine if Neil deGrasse Tyson posted a policy, or Neil Patrick Harris, or Neil Young.) Ideas must stand on their own merit, not on the reputation or wealth of the person who conceived the idea.
I'm not sure I understand your point about bribery. Are you talking about bribing groups of people to vote a particular way, or about bribing coercing powerful individuals not to express their opinions?
I disagree in practice that all ideas should have equal consideration. If an economist or other professional has a proposal, I think its practical to recognize that that person has extra credibility on a topic, and I don't see why we shouldn't let the public see that person's reputation. Professionals have an incentive not to state false claims--if the do so, especially in an internet forum board, they would be called out and their reputations would suffer.
On the other hand, there needs to be some anonymity to protect people from real life abuse. Do you see any problem with the option of anonymity?
You have some interesting ideas, and it would be rather helpful if you would add them to the wiki.
Your question poses an interesting problem. How do you give accreditation while still retaining anonymity? At some point you have to associate an account with a person.
I think optional anonymity would allow corruption into the system. (Televangelists, for example, would opt-out from anonymity so that their proposals might pass through randomized moderation by votes from their fan base.)
Much of this is putting the cart before the horse, though, as the system is probably best tested, at first, with politicians. See also: http://openparliament.ca/
Consider, too, that the system is self-referential. You could use the system to debate the relative merits of vote and comment limits, for example.