For the first point of view, if you need to display 0 on empty data, the only way is to implement the zero-fill function on the server side or JS.
I worked with the same problem a few months ago and had to implement on my server side, because the library does not have a built-in function.
Second point. Your date format is working fine, the problem is that you activated pan and zoom . Then you cannot scale and see the formatted dates, because categoryAxis.parseDates groups them in months. I suggest you turn off chartCursor.pan and set the minimum period on the axis of the mm or ss category.
Here is your modified script.
source share