that is not the manu fault, and actually not the installers. heavy winds can get up under a flap and bend it back and it will fly off.
I would say that this happens occassionally and its actually your responsibility.
As far as spacing or the spacing for each new course. I for one lay down the starter course and the next course will be alternatively throat designed to fit right on top and slightly over that below throat. If you have shingles with exposed throats, then you do have an installer problem.
These are easy to repair with the right tools Patrick.