As far as I know AndEngine GLES2 is one of the most versatile engines for Android. But there are others of course:
- Angle (java written 2D Engine)
- Rokon (more physics, and apparently good documentation)
- Libgdx (Cross platform development based on HTML5)
However I have never tested any of them but AndEngine. And yes, you are right, it is a little annoying to have so much unknown functionalities without any documentation at all (but the basic examples, that only show how it works and don't explain anything…). But AndEngine gets regularly updated and it works pretty good!
For your other questions, AndEngine has 2 main threads: the uiThread and the UpdateThread, so if you want to start an AsyncTask you may have to run it on one of those threads:
runOnUiThread(new Runnable() {
@Override
public void run() {
new AsyncTaskLoader().execute(callback);
}
});
And what about that 'switching layout within a class between scenes' ? I had isses, too, when switching between scenes. Elaborate your questions a little more and add some code, I am sure there will be someone who can help (and without documentation this is the only way to progress : )