Hi, as far as I know you can not see the comments in queries or plans as column. Comments are not an attribute and so you can not display them. You can open the work item e.g. in another view to access them.

Honestly I don't believe it would make much sense to try to show them in a query or a plan. They are typically too huge to see more than one work item in a row if you would display them. The same applies for the history by the way. It might be interesting to be able to configure the OSLC hover to be able to access them, but the size would probably be the same issue there.