Yes, there is a difference between descriptive politics and normative. But like economics, the two easily run together, in the minds of writers and readers alike. I think people are overconfident in their own ability to distinguish positive and normative discourse, especially in politics. Even factual descriptions can piss people off who are used to thinking the opposite. And while there's benefit to correcting their false beliefs, the chances of actually doing so are thin, and the chances of a forum-polluting flamewar or signalfest are high.

As for where to get advice, why not an avowedly political forum? You could start with whatever political blogs you frequent. The audience of such fora have already self-selected for interest in politics. You could probably ask professors of political science, too. Just find their contact info on the university website and write them an e-mail.

Good luck. It sounds like an interesting study you're trying to do.