I really only use flash for menu pages, I've only once or twice done animation or drawing.
It's quick and dirty compared to PS. PS you really can't just draw lines with a line tool. It creates a new shape layer and I haven't figured out what that all means.
Flash you can draw a line, then shape it, resize it, flip it, color it, pretty easily. I would consider doing the line drawings in Flash (if you don't have a wacom or illustrator) and then coloring it in PS where you have more layer/coloring options.
What you have looks pretty cool though.