Definitely some good points in there. I think that number 4 - overly monolithic social, ethnic and religious groups - is one that people should especially go out of their way to avoid, considering that it's not just abstractly 'bad practice'; it usually ends up making stories much more boring than they could be. Even in cases where there are strong social motivators, e.g. to participate in religious practices, there are still going to be people who are less than enthused.
Some very good points on there, great post :)