Hi Andrew, here's my 2¢ worth and it may be overkill but anyway here it is. I'd place a piece of plywood over the damaged area from the attic, then screw into it from below to firmly secure the damaged area to the plywood. Next sand off the existing finish around the cracks and screws, cover/fill with joint compound, then once dry sand smooth. The texture can probably be obtained while painting, you stated that it was a sandlike texture. You might be able to obtain some decent results by using the tip of the paint brush and poking. Anyway that's all I can offer, maybe someone else has some ideas. Good luck!