Unity 3D script player shoot bad direction - frame-rate

Question

I'm using Unity 3d version 4 because I have a MacOS X and I'm making a FPS 3D
I have a script to make the player shoot but this script only shoots up and does not consider where I point the mouse
Below the code in CS
Could someone please correct my script because I have been blocked for 3 days and I have not found any solution on the Internet. Thanks
using UnityEngine;
using System.Collections;
public class ShootDemo : MonoBehaviour {
public Rigidbody projectile;
public float speed = 100;
// Use this for initialization
void Start () {
}
// Update is called once per frame
void Update () {
if (Input.GetMouseButtonDown(0))
{
Rigidbody instantiatedProjectile = Instantiate(projectile,
transform.position,
transform.rotation)
as Rigidbody;
instantiatedProjectile.velocity = transform.TransformDirection(new Vector3(0, 0,speed));
}
}
}

Answer 1

The way you set the velocity is not right, you should get the mouse position like this:
Rigidbody instantiatedProjectile = Instantiate(projectile, transform.position, transform.rotation);
var input = Input.mousePosition;
input.z = 10;
Vector2 touchPos = Camera.main.ScreenToWorldPoint(input);
Vector2 dir = new Vector2(transform.position.x, transform.position.y) - touchPos;
dir.Normalize();
instantiatedProjectile.velocity = dir * speed;

Answer 2

I found this script in JavaSript working but the bullet speed is too slow and then the bullet stays in the scene for 2 seconds instead of making it disappear completely. How can I then add strength to the bullet?
var Effect : Transform;
var TheDamage = 100;
function Update ()
{
var hit : RaycastHit;
var ray : Ray = Camera.main.ScreenPointToRay(Vector3(Screen.width*0.5, Screen.height*0.5, 0));
if (Input.GetMouseButtonDown(0))
{
if (Physics.Raycast (ray, hit, 100))
{
var particleClone = Instantiate(Effect, hit.point, Quaternion.LookRotation(hit.normal));
Destroy(particleClone.gameObject, 2);
hit.transform.SendMessage("ApplyDamage", TheDamage, SendMessageOptions.DontRequireReceiver);
}
}
}