Uber app kicking me off when phone screen goes to lock screen

I just started driving for Uber.

Problem #1: The app runs in the background, uses 40% battery. So, when I am sitting in my car with the phone charging, the battery loses charge. I have tried settings to conserve the battery but it still drains the battery. Do you know a good link to suggestions as to how to save battery?

Problem #2: Do you know the settings to make the phone go to lock/black screen mode without being kicked offline? While waiting in my car, it seems the only way the app does not kick me off is if I have the screen turned on all the time. I think this is why my phone discharges. I have tried letting the screen automatically go to lock mode, but that's when after a period of time while waiting for the dispatch, it kicks me off leaving me to be sitting there offline and not knowing that I am offline. This is very unproductive.