Adding insulation to attic?

no it does not have to be blown in. You can lay in the roll type over the existing insulation. It's probably best if you lay it down perpendicular to the floor joists. If you have plans on doing the roof i would lay those on first ( I'm assuming you have no floor in the attic, you can drag a piece of plywood along with you while you work ). A respirator of some type and gloves are a must.