yes, the 3d frameworks you mentioned have the ability to load and manipulate models made in maya and blender.

check your thread.

Yes, you can build an entire 3d game in Flash and there's tons that already exist, including full scale MMOs in progress. There's no magic about Away3D, Alternativa3DPlatform, Flare3D, Starling, etc. They're a lot of sweat equity by companies who directly use the Stage3D API to make your life easier. You can build those frameworks yourself, including the physics engines. No magic, just knowledge and time spent.

No, you do not need Flash Builder either. You can do it using Flash Pro (the hard way) or grab something free if Flash Builder is out of reach for you, like eclipse+FDT (Flash Builder is built on eclipse). You will just have a harder time building your game, translating the tutorials from FB to E+FDT or FP. Most serious developers know how important both 3D and FB are which is why most tutorials involve that software.

That's fully possible and with certain frameworks and 3d software, pretty easy too. In a few dozen lines of code using Flare3D I was able to import a 3d model and access each part via the name I assigned in 3dsmax (exporting to f3d format using the plugin). I could then easily rotate/move/etc all the parts of the model. Framework to framework you'll have different options and certain things will be varying degrees of difficulty. Flare3D isn't free but it made it really simple to let me click a certain 3d object and start an animation I created in Max as well as individually control models.

That is faux 3d. It's a nice effort but overall it's CPU-bound. Stage3D is true GPU and utilizes real models via AGAL mini. It's up to the task you need with true 3d, shaders, etc. Definitely discard Papervision at this point if you're looking for true 3D. The feature set is limited in comparison to something like Direct3D but what you can do with it is still amazing considering the install base of Flash Player and the ability to deploy your true 3D interactive, real-time rendered content with no extra plugins.

Stage3D is an API built into Flash Player 11+:

http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/fla sh/display/Stage3D.html

Here is an explaination of it and links to several frameworks that do all the hard work for you (some free, some commercial, etc):

http://www.adobe.com/devnet/flashplayer/stage3d.html

There's plenty of showcase examples there. Stage3D will be a huge part of Flash's future. Starting now would be good. There is no more need for papervision-esque faux 3d engines.