Great to hear SourSwallow36 , contributions are always appreciated 🙂
Regrading (3), MongoDB was not build for large scale logging, elastic-search on the other hand was build and designed to log millions of reports and give you the possibility to search over them. For this reason we use each DB for what it was designed for, MongoDB to store the experiment documents (a.k.a env, meta-data etc.) and elastic-search to log the execution outputs.

Also, I would like to add some other plots to the dashboard. I

Do you mean like a dashboard to web UI home screen?
Or is is part of the training process that you want to visualize?