Airbrush your primer, never hurts and can help adhesion, finding mold lines, seams, etc. If you have large areas of a single color, such as a cape or a greatcoat, you could airbrush that, however, the common pratice is to paint figures from the inside out. Since flesh is the most critical factor and the face the most critical flesh area, that should be done first.
In general figure painters use brushes. I've used enamels, oils and acrylics. I currently use Andrea/Vallejo almost exclusively. The effects rival oils and drying time is a lot less, For figures, your worst choice is Tamiya. The reasons are manifold. If you can't get A/V, go with Model Master or PollyScale acrylics. ModelMaster enamels ar eht ebest and if you go with oils, choose "artist" quality rather than "student" qulaity since hte pigment is a lot finer.