Is it advisable to use oils + airbrush? Would the effect be better than enamels + airbrush?

Other than maybe for the purpose of "misting coats," I don't think oils should be airbrushed. This is because they are, by nature, quite transluscent. I don't expect you'd be able to get the coverage you need. Also, thinning them to a proper consistency may be difficult. I certainly think enamels and acrylics are better suited for use in an airbrush.