First Character and loose hit points

the first person controller that comes with unity has alot of bugs when you attach a rigidbody. Here's a simple script you can use as a move script. just add this script to whatever you want as a character and go to component/camera-control/mouse look and add it and also go to component/physics/character controller and add it.

public var MoveSpeed : float = 50;

public var jumpSpeed : float = 55;

public var MoveDirection : float = 45;

public var grounded : boolean = false;

function Update(){

        if(grounded){

                  MoveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));

                  MoveDirection = transform.TransformDirection(MoveDirection);

                  MoveDirection *= MoveSpeed;

        }

        if(Input.GetKeyDown(KeyCode.Space))

         {

                   MoveDirection.y = jumpsSpeed;

          }

}

MoveDirection.y -= Gravity * Time.deltaTime;

var Controller = GetComponent(CharacterController);

var Flags = Controller.Move(MoveDirection * Time.deltaTime);

grounded = (Flags & CollisionFlags.CollidedBelow) !=0;

}

as for hit points per speed you would actually have to adjust the script by adding drag to just about everything so that you would be moving different speeds depending on how long the button is held, released, gravity and adding a top speed for acceleration and gravity. Maybe using something like if force = a certain amount then -- hitpoints. sorry i can't be too helpful on that