I am still confused by the concept of water based car paints. What happens when it rains?
Best to use oil paints, although quite difficult to hide the brush strokes.
I think the best thing to do, from a application technique point of view, is to stick to a method that works for you. As I think was already said, the results are ultimately the only thing that matters.
Usually, however, with something so important to the aesthetics of the car, we rate the success of the job on how it looks. However, With paint there is more to it and this is where the application methods can be more critical.
Our paint, for example, is applied while the previous layer is still slightly wet. This is partly to do with speed of mass production process but also because the paint is designed to be sprayed wet-on-wet in order to get the best performance results (adhesion between the layers, resistance to water and humidity etc). These are the key factors in making sure the paint does it's functional job but they have to be controlled fairly carefully otherwise you get easily get problems with appearance (dull lacquer, bad dispersion of metallic flakes etc).
Thickness of the basecoat layers can affect colour depending on the type of paint and opacity (coverage power). With metallics, the thicker the coat, the more the flake will float around before it dries. This may affect the colour and appearance of the paint when dry. With our process we would use a silver paint formulated to give good colour & coverage at a thickness of between 10 to 20 microns. Again, this may be different with re-finish paints.
The only thing that really worried me from the earlier posts is the idea of flatting the basecoat.
Anyway, sounds like you guys have everything under control.