Source: Experience. I'm still an Expert on Battle Subway and I don't even have 50 points.
And you will become an Expert if you hit 6,000 points. They're not handpicked, and if you prove you're good, you'll get the others too.
EDIT: If you gain 1,000 points and become able to edit in Meta/Battle Subway, those privileges are not transferable to the other sections.