Welcome.
Have you read and used this tutorial HOW TO: Program the native SpeechRecognizer for Continuous Dictation and to do things
The example Project has a feature to Use Timer and another Auto Sr. Turning both on might provide the response you need to keep the app running. Keep in mind, if the Screen is not touched within a period determined by your device System settings on your tablet/cell phone, any app, not only your app, will 'go to sleep' . Use an extension to make the app work in the background or use a StayAwake routine to force the app to run continuously.
Regarding your second problem, Parrot contains some code to respond to if a command is not understood that may or may not ameliorate the tendency of your app to stop. You need to use if..then..else statements to help the SpeechRecognizer to do what you want. Setting Use Timer and Auto Sr might help you with this issue too. Review the code and Clock settings in the aia and adapt them until your app 'works'.
Unfortunately, App Inventor does not have access to the full SpeechRecognizer library that can be accessed using a professional compiler so one has to use the tools available to make the SR respond better.
My French is terrible. I once was lectured in a restaurant in Northern France in the countryside when I ordered a fish. I could not pronounce truite .The waitress would not provide my order until I pronounced trout correctly. 
I am not going to be able to test your aia.