If we have a clear and explicit set of baselines, it will be easier to judge a new technique against it. For example, a technique that is not implemented in the main browsers is not appropriate. My personal preference would be to include these checkpoints. This is the place people go to get guidance for people with disabilities. A usability checklist doesn't cover these issues.
People expect to see all disabilities covered.
If so, usability is part of accessibility. I think we have agreement that we can separate comprehension and browsing into two guidelines. We should be able to take the checkpoints and order them alphabetically. It doesn't matter which section they are in. It just helps us.