On the last point, one thing I've taken away from the HN karma system is that your votes are most highly correlated with the general traffic around a discussion, more than with anything specific to the comment. Posting almost anything decent on a story that sits on the front page for a day will get you double-digit upvotes, especially if it's an early comment. But posting something in an article that only briefly hits the front page will not get much attention.

Come to think of it, that does transfer to both business and academia to some extent.