Hello,
I am Actionscript 3.0 programmer working in Flash, Flex and Adobe Air for all platforms from desktop to mobile. Recently, my priority has shifted to Mobile Apps using Starling/Feathers (a light weight completely new AS3 classes for mobile platform). Please check my reviews and feedback for further references. I have outstanding reviews.
Regarding the project, the first thing is can I have the swf file, not Fla file. So that I can give you clear cut information on this. AS2 can be changed to AS3 without any doubt, but there are restrictions while moving to mobile platforms. If the application has plenty of animation, then Starling/Feather is a must. Otherwise, regular AS3 classes can also serve the purpose. I believe by mobile app, you are referring to both Android and IOS platform. For this, we need to have a developer account before publishing the app in Play Store and APP Store. First, please send your swf file, then we can discuss further.
Regards