Apart from the language differences (class-based vs prototypical, strong vs weak typing), what are the differences between using Javascript and using C# when developing games in Unity3D?

Is there a noticable performance difference?

Is the javascript code packaged as-is? And if yes, does this help the game's modability?

Is it possible to use libraries developed for one language while developing in the other one?

Is it possible to mix the two languages in the same Unity project by coding some parts in C# and others in Javascript?

The next couple of questions are time-specific so feel free to ignore or remove:

If libraries are not cross-functional, which language has better library support from the game development perspective?

Which language has better game dev specific resources available (books, websites, forums)?