RE: How to reference the native highcharts library from NetSuite
I don’t have the answer, but something for you to think about. (not preaching, just a friendly warning)
You probably shouldn’t based on the fact NS will be paying a license to use it and that likely doesn’t extend to you using it.
That being said, if you’re using it client side you can probably dig through the console and see how they reference the object(s).
Just be warned, if they ever move away from using it (as they will be doing with EXTjs), your code will fail.