When it comes to pulling in requirements for a dashboard, the number one requirement I have is "what is the core point of the overall dashboard?" Your questions are good, but may create a "metrics at the cost of use" mindset where people are so worried about building metrics and pre-answering questions that they don't just sit down and build something useful, quickly. Also, your approach may work against interrelated dashboards that drill down from one to the other, a good usage model I've used very effectively, and you also see on the monitoring console (MC).
Dashboards aren't something to be greedy or stingy about. Let people build them.
That said, my core rule of thumb is something you may not have noticed: Good dashboards minimize scrolling. That means that a well written dashboard, users don't have to scroll (much). Use pop-up panels (with close links for the pop-up), use drill downs to other dashboards or just build highly targeted dashboards. It helps, a lot.
