If you have stucco,(lath & plaster) contractors in your area, It might be wise for you to find one that will do your project as a "side job". They will have all the materials needed for your project, probably from other jobs, that will be more cost effective in the long run for you and it will be done right. The main concern is the lathing being done correctly so you have no leaking there as stucco, or even the old hardcoat is not waterproof. It needs to be lathed/flashed correctly for a dry project. You could do the framing and the painting to match as a patch is best when scratch/brown coated, then painted to match rather than trying to match up with a stucco topcoat. If no luck finding someone reputable, e-mail me and I'll walk you through it. It will take up too much space here on the forum to explain in detail all the steps as well as asking you further detailed questions. It's not rocket science, but patches seemingly simple projects can be pretty involved to make it right without causing problems down the road.