Welcome to the detailing world, it can be fun and rewarding to learn how to take care of your Bimmer. I personally enjoy getting into a nice clean vehicle that looks great, not to mention it really helps when selling.
As for the clay bay some people will tell you that you should go with the air flow, or in a specefic direction. IMO it shouldn't matter what direction you work in just make sure you knead the clay frequently and use plenty of lube. As for how many passes over an area it varies. I pass over each area of the car atleast twice and more near areas with contaminates, etc.
Let me know if you need any help with the rest of the detailing process or selecting products. We have a great set of products that get outstanding results, plus you get 10% off. Good Luck with the detail and let me know if I can help you.
Greg @ Detailed Image