Not sure I'm following your stenciling question, but I haven't had success stamping with stamps made from molds. I experimented with that recently and the imprints have been pretty bad - at least not what I'm used to. The mold that you're going to use also has to be perfectly flat on the bottom in order to work in reverse as a stamp.
I think airbrushing would be the faster, more reliable way to go. Anyone can cut you the stencil you need, and you can crank out a simple stenciled pattern in seconds.