A couple of style questions
 

Is it possible to make the "Allow Users To Change Styles" option apply to specific usergroups? I would like some to be able to change the style, and others not.

Is it possible to make some styles selectable, but others not? For example I don't want people to pick the default style. I have also purchased a style and then customized it by making a child style. I would not want people to be able to choose the non-customized one.