strange android problem, and correct way to restart android container, and android apps behavior on FLX1s

On the FLX1s when the android container is running:  

1. At times the android apps start looking strange - they stop filling up the entire screen - and stop working.  What causes that, and how do I fix that?  
2. What is the proper/clean way to restart the android container?  
3. Using an android app like Signal as an example:  When I power on the phone, and also the android container starts, will Signal be active in the background ready to accept messages and calls?  Or, for every android app that I want active do I need to manually start it and never swipe it away?  (In settings for android I didn't see anything for background jobs or battery optimization.)