Some questions

So, I've got a few questions to ask.

1. How am I able to send notifications from the Khan Academy Support Center (here) to my ordinary Khan Academy account, so I know what's happening?

2. I'm making a PJS program, and I'm considering adding music to it. I want to know how to make music notes without breaking any of the guidelines, like Squishy did with his program.

3. Is there any way to detect if the ESC key is pressed? I've tried the keyCode for it, and it doesn't seem to work.

4. I'm making an editor, and if you have a mistake, there will be a red text under it saying the error. But it doesn't clear away. It's at the bottom of this webpage:

https://www.khanacademy.org/computer-programming/dont-look-yet/5532520264187904