With regards to taking up AS3, there are some books that I highly recommend, in this order: http://www.friendsofed.com/book.html?isbn=1590597915 (Foundation AS3 Animation) http://www.amazon.com/Advanced-ActionScript-3-Design-Patterns/dp/ 0321426568 (Advanced AS3 with Design Patterns)
The first one's an easy read and a good reference. The second gets useful when you reach the point that you're noticing patterns in your different projects' code, and are thinking about abstracting them.
If your book budget is small, there're also free references online to help you out, though they read like c**p (as they probably should):
http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/ (Language Reference) http://livedocs.adobe.com/flash/9.0/main/Part1_Programming_AS3_1.html (Programming ActionScript 3.0)
As for porting your AS2 project over, you may have some difficulty with that, depending on how much of your code in in the .fla file. I suggest you develop a simple game (like Pong :) to get the hang of things before attempting your port. I expect that most of your code is reusable, but you may want to refactor large portions of it to work more intuitively in the new language.
Best-a-luck!
-Jeremy