First question : You're absolutely right.

Second question : Usually an entity pointer refer to a single object at the
same time, in your example, there will be no error but the engine didn't know
which missile you're refer to at runtime, so better rewrite your code with my
or me pointer as follow :

Code:

---

function moveMe()
{
  my.x += intXoffset;
}

action assign_projectiles
{
   .....
   while (my != NULL)
   {
       moveMe();
       wait(1);
   }
}

---

Then, each entity (missile) has their own movement.

Third question : It is possible also, but why doing this way?