2wheels chassis

Hi, i want to know, may i use apm:rover for my robot with 2wheels chassis (two drive wheels and one supporting)?

Yes, you can ArduRover2 firmware and the skid steering function to control your rovers speed and direction.
TCIII ArduRover2 Developer

And i want to use proximity sensors for automatical mode. I can use arduino board or need to buy PX4 board?

and model of sensor is PX4flow v1.3