How would I make 2-3 background planes (with textures for the backgrounds) move at different speeds as the player moves through the level to give a more lively feel to the game?

Like hills move slower then buildings in front of the hills all an orographic camera with 2d images?

function Update() {
    // Move the object to the right relative to the camera 1 unit/second.
    transform.Translate(Vector3.right * Time.deltaTime, Camera.main.transform);
}

http://unity3d.com/support/documentation/ScriptReference/Transform.Translate.html

That moves the the objects (Background or w/e to the camera, should work well for a 2D game, might need to change Vector3.right to Vector3.up or Vector3.forward.

Good luck!