Hi, always use a primer before top coats as this helps the top coats stick to the object you are painting as well as showing any fault or flaws in the plastic or your build thus saving you a whole heap of swearing when you notice something wrong in the underlying plastic. White is the best primer if you are going to spray yellow as it helps with the opaqueness( easyly seen through) of yellow. Have you tried getting the blue Angels yellow in the Tamiya spray cans?
Airbrushing is the way to go but will require serious thought as to type(single or double action), compressor and accessories ie; water trap. It will be a big dollar purchase so I recommend careful choice. CHeers