I'm going to make an attempt here, but you may need to help me help you a little.
1. Everything in Android is serializable. Most of the OS is pure Java which is already reduced to bytes and the OS is also saved in ROM instead of disk or someplace else.
So approaching your project in the scope of "serializable" is probably going to give you an efficiency advantage since parsing always takes an extra processing step. However, this is usually only necessary for video games and hardware management software.
I would really like to know more about your project, if not for sheer sake of curiosity.