Custom Android 4 rom

Hello, I have an app written for android 4 and the tablets that will run this app will be dedicated to this app, therefore we need to disable the buttons on the bottom menu bar and the side buttons of the tablet that I will be using. It is a tablet that will be produced specially for me by the far eastern tablet pc manufacturer, therefore we are free to load our software on it. Requirements are: -There will be no shutting down of the tablet, if it runs out of battery, whenever plugged back in, it will restart and our app will run immediately -There will be no way of exiting our app and using the tablet as an entertainment device. -If for any reason the app fails and crashes, it should be restarted immediately -The tablet won't support the usb port on it, it must be disabled Can you do that? If so, let me hear your experiences and your methods. Thanks