Juice

I just started spray painting for the first time. I'm committing a scale modelers sin by not practicing something I've never done on scrap first (although I did test for paint compatibility). So please try to bear with me and my newbie questions.

1) When spraying relatively small areas of the entire piece, what do you do to mask the large areas you are not painting? I'm painting the white arrows and the white part of the stars and bars first. To protect the rest of the fuse and wing, I used large pieces of scrap paper I saved when unpacking my new furniture. One of the attached pictures shows how I did the masking. Is there any better easier way?

2) I made a newbie mistake by not spraying primer under the white. The consequence is that I had to spray many thin coats to get the colour even. When finally even, it seems thick but can't really compare with anything (but the panel lines still show up very nicely). I an using automotive paint and frisket paper to mask. When pulling up the mask, the paint sometimes wanted to lift up in small sections, especially at corners. The largest section that lifted on the inboard bar beside one of the points on the start on top of the wing. I will have to fill that in later. Does this mean I should be taking off the mask sooner, before the paint starts to dry? Or is it because this layer of paint is too thick?

3) My next step is to mask the white and then spray everything else blue. How long should I wait before I mask the white? A day, a few days, or maybe a week? Should I wait for it to fully cure?

Thanks,
Juice