Hi Eric, thanks for answering so quickly.
With my second question I mean that the HTMLEditor would work with a textarea that has focus. So if I type something in the first area, the HTMLEditor works for that one and when working in the second field, the same instance of the Editor works for that one. That way you only need one HTML Editor per page, making the forms a little bit more user-friendly (and less challenging for inexperienced users) in my opinion.
I'm now going to try to hide the HTMLEditor for a field if it doesn't have focus with some JS.