wow... you have an indepth plan to for the dashboard. In my case this is a very early conceptual phase and I may borrow some of the approaches you have mentioned. It would be more of a pet project and will improve, add features as and when we integrate the various tool sets.
Once i know what data can be achieved mainly via the REST API calls (Installing logstash, beats on the servers where the tools are installed is a bit challenging and need to hop around a lot of process/permissions to get that done), i can then plan around the dashboard. I have requested access to the available Elastic stack instance and will start with some development. I will keep posted on the progress