1) There is no developer license for for Flex/Flash. The only one charging developers for licenses is Apple.
2) When developing mobile apps, you use touch events, NOT mouse events. Adobe and Apache have been good at developing mobile libraries.
1. I'm pretty sure that Adobe charges money for their Flash SDK. I researched this a couple years ago. The open-source Flash SDK isn't as good.
2. The problem is OLD Flash content won't work on mobile, unless it is re-written specifically to work on mobile.