I agree with most of the postings about velcro or a nose that fits over the existing nose. I am currently the art director for a community theater group, and I can tell you that one axiom is that you don't design for what you can see up close, you design for an audience that is at least 20 feet away. If you can't see velcro from 20 feet, you are probably safe using it.
If I were you, I would use the styrofoam bust as an armature for the sculpture. It will save you time and energy, and since you are probably not being paid for this, I wouldn't waste time building chicken wire armatures. Use a fine textured paper, such as paper towels, as your final coating on the sculpture, and you can save yourself priming the bust when finished. As a matter of fact, I developed a way of using paper towels or tissues dipped in glue to make a type of paper clay that would be ideal for adding details to your sculpture. I would be glad to elaborate if anyone desires.