Help me finish the script - shoot at raycast

Hi.
Total beginner here so keep that in mind.
Got that far to shoot arrow from object.
Now I need to change this script (and do other things if needed) to shoot from that capsule to where I click with mouse at certain point on that raycast thing.
Script (as good/bad it is, it is working this far):ProjectileShooter.cs
And as far as I understand this guy got it working:
http://answers.unity3d.com/questions/763289/how-do-i-ray-cast-shoot-to-mouse-crosshair-from-me.html
However my camera wont be moving around so it probably shouldn't be as complicated.

Basically to incorporate necessary parts of it in my script properly. I can't do it yet... Unity doesn't like whatever script mixture I'm giving it.

 

This is what I would try (but I'm a beginner too!)

get a vector3 of where you clicked with the mouse,
then instaniate the arrow wherever that is and get it's location
then Lerp (instaniationlocation, mouseclicklocation, speed)

This is how you can get that first vector 3 - shoot a ray from dead center of the camera to where ever it collides

Code (CSharp):

1.   Ray cameraRay = Camera.ViewportPointToRay(new Vector3(0.5F, 0.5F, 0));
2.         RaycastHit hit;
3.         if (Physics.Raycast (cameraRay, out hit)) {
4.             Vector3 hitPoint = hit.point;
5.         }

 

Here it is:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class ProjectileShooter : MonoBehaviour {
5.    
6.     GameObject prefab;
7.     void Start () {
8.         prefab = Resources.Load ("Projectile") as GameObject;
9.     }
10.     void Update()
11.     {
12.         if (Input.GetMouseButtonDown(0))
13.         {
14.             RaycastHit hit;
15.             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
16.             Vector3 aimPoint;
17.             if (Physics.Raycast(ray, out hit, 500))
18.             {
19.                     aimPoint = hit.point;
20.                 }
21.                 else
22.                 {
23.                     aimPoint = ray.origin + (ray.direction * 500);
24.             }
25.             GameObject projectile = Instantiate(prefab) as GameObject;
26.             projectile.transform.LookAt(aimPoint);
27.             Rigidbody rb = projectile.GetComponent<Rigidbody>();
28.             rb.velocity = projectile.transform.forward * 40;
29.         }
30.     }
31. }

Works OK, more or less. Doesn't hit the projectile exactly where I click, but at least it is consistent and it actually can work for gameplay mechanics. The projectile is affected by gravity after all.

Now I can't figure out how to destroy that projectile after 2 seconds. I can't have scene full of projectiles.
Only thing I manage to get is Destroy-ing a thing after 2 seconds, but the thing is not the projectile(Clone) but the shooter. If I make camera to be projectileShooter then it Destroys camera after 2 seconds. Same with Capsule or any other object that I turn in to projectileShooter.

How to fix this and properly destroy every new projectile(Clone) after 2 seconds?

 

OK I found how to destroy it. I was trying to do it from within shooter script. Best thing that worked that way was Destroy(GameObject.Find("Projectile(Clone)")), but the problem there was that if I shoot multiple projectiles in a row it deleted only last one. Couldn't keep up or something.
What I actually had to do was to create a new script file and attach it to projectile prefab itself (the object that is loaded, cloned and shot).

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class destroyClone : MonoBehaviour {
5.  
6.     void Update () {
7.         Destroy (this.gameObject, 1);
8.     }
9. }

Now I shoot it and the thing disappears after 1 second.

Problem is, that in some posts peoples forget to mention it, so I go mad trying to do it from within shooter script.
But thats OK. Experienced peoples tend to assume that other know stuff already.