I think this one is easy: They shouldn't be.
Columns and editorials are great candidates for being available only in the print edition of the newspaper. Even though they're often written off the news, they're seldom so timely that posting to the Web is an advantage. So, I'd make well-written columns a good reason for readers to pick up The Orion on Wednesdays.
A good replacement would be subject-specific blogs. A student-government blog, for example, could be a wonderful way for the A.S. beat reporter to keep visitors to theorion.com up to date on what the organization is doing. These are often things that don't warrant a full story in print. Finding something to write about a few times a week would also make time spent on the beat worthwhile for the reporter and would probably lead to more and better print stories about A.S.
Lots of other ideas come to mind: the police blotter (this could duplicate what the paper already does or pick something out-of-the-ordinary out of the police reports for 100-word-treatment), student club news (with lots of names in bold), politics, a person-on-campus vlog, an overheard-on-campus humor blog.
Reader opinion is trickier. When I ran my own hyperlocal blog, I decided to push all reader responses to my Facebook page where people would be identified in some meaningful way and associated with their opinions. One of the things that ruined the StarTribune website for me was the garbage some people would post on stories that had to do with people of color, gay people, President Obama and all the other potential targets of hate. Because they could hide behind their anonymity, they said anything and everything they'd never say in public.
I'm not generally a fan, though, of pushing website traffic to Facebook to help Mark Zuckerberg and his stockholders get rich. I am a fan of making it easy for readers to become part of the campus conversation through their newspaper, even those who won't take the trouble to write an actual letter. So, I'm still thinking about an ideal solution.