Here are some pointers to get you started:
- Web-cam streaming from the Raspberry Pi:
http://blog.oscarliang.net/webcam-streaming-video-raspberry-pi-via-browser/
Note that streaming video over wi-fi will inevitably lead to a delay of up to a few seconds.
- Controlling a robot remotely via Bluetooth (including example of using ultrasonic distance sensors):
Arduino robot controlled from an Android phone via Bluetooth – 42 Bots
You can use other Blutooth devices (like a Wii mote instead of an Android phone) with relatively minor updates.