I would raise all these issues and more in group meetings. Try to get people to understand the many different benefits review brings to both the committer and reviewer - by having them state the benefits they want or could see getting. Talk about various kinds of comments (clear bugs, performance, style, robustness, factoring and organization, etc.), and the various priorities from no-action-required to nits to blockers. Talk about the priority of reviews themselves. Reducing the latency of reviews has a huge positive effect, ime.