In the attached pictures, is this "popcorn" treatment of the ceiling?

http://i34.tinypic.com/18ok1z.jpg

http://i34.tinypic.com/30w8ccp.jpg

Whatever it is, it is kind of "crumbly" and if one touches it or
brushes against it hard, it seems to fall off in little crumbs.

We're thinking of repainting the room, and I wonder if I can simply
scrape this off the ceiling and repaint? SHould I put on a primer?

It is in an upstairs room and I'm also not sure if this treatment is
perhaps partially an insulation, although I doubt it.