1) No. URMs are typically African American, Native, or Hispanic. At a school like Columbia, or any school in New York, Russian Jews are pretty well represented.
3) When I applied, and this was three years ago, they did notify me when they'd assembled all of the necessary stuff. But, they never gave me updates. It was just them letting me that they had everything and then, a while later, a decision. Of course, that could've changed.