the header icons are a topic for itself. Recently I applied the help icon + help text quite often

In my experience not a lot of people seem to care about (both developers as well as users), but to me the header icons on shapes and filters are noise which should be taken care of, so fully supportive of your suggestions (and I'm always ensuring it myself). I would be careful with changes in PBI Service as it's too easy to get out of sync with your offline copy.

If I remember correctly, the toggle to view/not view header icons can be set in the themefile. But maybe not the individual toggles for each particular icon(?)

Nice video! Is the IBCS-like bar chart done with SVGs or you did it some other way?

I think it's useful to be able to do it in the service without having to use the actual PBIX file, but the downside is later on. If you go and make a modification to your existing PBIX file, those changes won't persist as changes are not in sync with the file. Unless you're downloading the latest PBIX file before making changes that are not available in the service. I still think it's better to do it using the desktop app

I think a lot of these should be set by MS as the default setting. The maintain layer order, is a prime example, and I honestly can't think of a reason to want the current default behaviour...