Upgrade your flash then get back to us.
I am going to have access to a full Adobe Suite in the Fall, I want to do the bulk of the work in text editors and Flash8 before I leave for New York in August.
You may share whatever resources you would have shared if said "I have the most recent version of Flash."
Building a game is no small feat, especially the size in which you entail. There are so many technologies available today you can leverage to aid you that you can't use I wouldn't even know where to begin.
Here's a start. Take a look at the Stage3D API and classes. Half way down this page links you to several frameworks (Flare, Alternativa, Starling, etc) that are designed to leverage the brand new GPU powered Stage3D framework. They do a lot of the work for you.
For your purposes I would look into Starling first. If it's going to be on Facebook then your audiences computers capabilities will be the entire gaumet from horrifically old win98 laptop to brand new ivy bridge 64gb ram RAID0 SSD gaming rigs. You need to cover them all. So you should start off from the gates using the technology Adobe is promising will adequately power online gaming in the future.
The ever popular Facebook game Cafe World was a good example of AS3 simply not handling lots going on at the same time. It would even bog down a quad core. People would argue flash is not threaded and can't utilize more than one CPU but they don't understand how a CPU works. Aside that, Stage3D removes this problem and opens up the gates up to (as Adobe states) 1000x faster speeds.
Starling is 2D. It is very easy to use and has support from Adobe. They have some nice tutorials to get you up and running.
Problem is, you're on Flash 8. So I'd download the latest Flash Builder and Flash trials. Use Flash Builder to code in and use Flash just to manage assets. Flash CS6 can now even cut out its own spritesheets so you won't need something like Texture Packer (free) to make sprite sheets.
After you make your assets in Flash (graphics, audio, etc) and give it actionscript linkages (classes) you can export that as a SWC. This is optional, you can do the whole thing 100% in Flash Builder, but it's much faster in Flash. Regardless, then you import your SWC into Flash Builder (4.6 is the latest). Make sure you update to the latest release version of Flash (11.2) and AIR (3.2). Then start doing Starling tutorials.
You will find the vast majority of tutorials on any Stage3D or advanced content and examples to be Flash Builder tutorials rather than Flash. There's a reason. It's a better coding app.
There are alternatives to Flash Builder like the FDT eclipse plugin or FlashDevelop. Although not many tutorials utilize them and you'll find yourself spending a lot of time converting what they say into how your particular software does it. And sometimes your software can't do it at all.
If you have any very specific questions, fire away. It's a little large of a target to just ask how to code a game though. But there's a good place to start.