[AS3] How built in are Flash's Built in Classes?

Sorry for the cryptic title. As with most of my questions, I really have no idea what keywords to search for, so I turn to these faithful forums.

If I understand correctly, all classes in the fl.* package are written in pure ActionScript and exist somewhere on my computer. (I believe “C:\Documents and Settings<USERNAME>\Local Settings\Application Data\Adobe\Flash CS3\en\Configuration\Classes\FP7” - found it once before by accident, and found it now again doing a search for *.as files on my computer… ugh… a really long list.)

However, many features in Flash (seems like most flash.* packages) cannot be completed using only Booleans, ints, Numbers, Strings, and if statements. Some “advanced” features such as capturing user input (either from Mouse or Keyboard) cannot be handled directly (or are at least locked off from the user) There must be more than just ActionScript hiding inside the flash.display.DisplayObject for it to be able to have so many features.

Some more examples are Sound, Loader, Sockets, and Graphics, which need some sort of backend code in order to actually do anything.

Another related idea, since nearly all SWFs out there use such classes as “MovieClip” or “Sprite” (among others), is there always a “MovieClip.as” class included when compiled (and added to the total size of the final SWF)?

Would it not be smarter for each instance of Flash Player to automatically contain all (or most) “Adobe written” classes that are needed? For example, someone running Flash Player 10 will have all of Flash’s classes built in, so the only space that the compiled SWF needs is the developer’s custom classes (including the class created by the timeline). Since Flash Player would already be downloaded installed on the user’s computer, SWFs would be able to load much faster since the major AS files are already on the user’s computer!

Just to forwarn, if Flash takes this idea and incorporates it into the next Flash Player, I want a royalty, or at least a free upgrade to CS5!

To sum up, my questions are:
[INDENT]1. Which classes are “advanced classes”, and which are written by the Adobe team in pure ActionScript?
2. What is this backend? Are there any more detailed descriptions of the inner workings of Flash anywhere?
3. Are there any classes “embedded” with Flash Player?
It is 1:30AM for me here, so if there is anything unclear, please tell me. I work best at nights, but I’m not sure if the things I write will still make sense in the morning. :puzzle:

I predict Senocular will be all over this thread with another cool link or lengthy and helpful explanation in less than 12 minutes (or 24 minutes for long replies, not links) … :sen: