Traxxas trucks can't be controlled by a phone. That wouldn't even be a beneficial feature. The Traxxas radios will send telemetry data to your phone so you can monitor amp draw and speed. I don't see the point personally.
The Traxxas stuff doesn't keep the truck from flipping. There is a feature on some of the newer Traxxas monster trucks that will run the wheels back and forth to turn it back over if it flips though. That's pretty handy.
As for radio choices, you'll want end point adjustments, reversing, model memories, and exponential. That allows for the same radio to control multiple vehicles and be tunable to get just the right feel in driving. There are some RC vehicles that require more channels such as crawlers that have 4 wheel steering, but most only need 2.