is C# necessary in making a game, because ive been only focusing on javascript but ive been reading in a few places that i am missing out on alot not going with C#. Is this true? How much am i missing? 
Not much, as of Unity 3.0.
Many people (including me) have created commercial games using nothing more then Unity Script.
Use whichever language you prefer.
The only difference that I already felt was the plugins,because in javascript you can’t access .dll files:
There’s no reason not to use C#. Granted there are more Unity specific examples and tutorials for UnityScript, especially on the simple side, but there are way more general programming examples, books and tutorials on the C# side. But you are not bound to one or the other, once you know one well it’s not to hard to switch if you need to.
Jessy, nice link!