1- well you’re gonna wanna make an “Autonomous Switch” that allows you to switch between autonomous mode and R/C mode. I believe this plugs into the competition port. It’s pretty easy you can buy all the stuff at radioshack.
2-Dunno. I’m not a programmer.
If you have a switch on your control system (or just one of the buttons on the joystick), you can have that execute your autonomous mode for testing. If you know how to, though, just do what NeedMoreEngines said and make yourself a switch.
In the long run, it will be beneficial to make one of these switches. You can use my suggestion above until you have something like this, but you do not and cannot use that during an actual competition.