Thanks for the "thanks" everyone.
I decided to create an installer first before looking into the other things. This way, I hope a few people can test whether it works on their device (see first post for the APK).
Some notes about this:
- The installer holds the app_process executable and the XposedBridge.jar as assets and can install it to the correct locations (root permissions required!).
- It will automatically create a backup of /system/bin/app_process at /system/bin/app_process.orig, which can be restored either via the app or via shell (e.g. adb, works in recovery as well).
- I have only tested it on ICS (LPQ Stock). Honestly, I do not have the time to test it with anything below that. If somebody wants to do this, I can help you to get started with the code. app_process was not changed very often, so chances are rather good that it will work with only few changes.
- The installer requires SDK15 (4.0.3) for the same reason.
- Improvements for any part of the code are welcome! It should be easy to use for both users and developers.
- (Un-)Installing the installer app alone does not change anything (at least not now). Please use the buttons inside the app.
The next step should now really be to load modules dynamically, I hope I can use standard installable APKs for that (although the framework will probably request enabling confirmation for technical and security reasons).