Answer to your first question, there is no 1 right way to paint bare metal. Professional Paint/Body folks have used different systems for as long as paint has been around. Keep studying and use what you are comfortable with when the time comes.
Second question, if you are concerned about the paint flaking off because of the smooth toothless surface then scuff them with a Scotch Pad before you paint.
BTW, I am not a professional Paint/Body man so these are just my observations.
Fun project, enjoy.
