For to understand what happens, add -keep additional compiler argument (this will save the generated files into directory where your document class / application class is.
The files of interest would be those which have a name of this pattern:
As to the order of execution:
// Assuming we've done all the SystemManager
// stuff and advanced to the frame #2, which your code actually is
1. Call mixins (thise are static functions called before Application is instantiated.
2. Call the top-level document constructor.
3. Call recursively initiated(document, id) on the top-level container, container's children, grand children etc.
4. Do layered instantiation and layouting of all the visual components which are children of top-level container.
5. Dispatch applicationComplete event and wait for further instructions
Imports aren't called, they are used by compiler as a "lazy" data base for information on how to compile the class. What this means is: when the class is compiled, the compiler, once it encounters unknown reference checks local skope, class skope, package skope, and then if the reference is not found will go to the imports and try to trace the imported source.