My opinion is that it belongs on Meta, as it asks a direct question about the SE engine. Though, [Marc Gravell](http://meta.stackoverflow.com/users/23354/marc-gravell) says that it belongs on SO because it can be used as an example and generic question about the used programming technique (URL rewriting), and he has a point <sub>(and a diamond, don't forget the diamond)</sub>.

I'd reword the question to be more generic and leave it on SO.

About the others, those are more direct questions about SE-specific things, as far as I can see.