I'll try and answer your other propblem later, gotta rush now...but to be honest I am not a modelling guy and would like to know the answer to that myself.
Just to let you know that nailpolish is an organic solvent and dissolves platics really well. But the concentration in nail polish is pretty low, but the problems lies with people smackin it on like they would with Peanut butter. A little goes a long way, just a coat, very lightly like you would use Vegemite on toast.