We need more robust and useful documentation regarding how to use Data from an analysts perspective (or anybody writing queries).. like creating a Data/Product Analytics FAQ or one documentation that’s more clearly organized by topic.
A page with things like why some fields use structs, the fact that the fields are mapped to from JSON types, what controls that mapping, general table layout, how the whitelist works, how to do historical queries (where you'd put an infobox or note about hey, if you're using fields that got sanitized, then there will be NULLs) etc.

It would be helpful to start collecting the questions we get (when we get questions), from PMs and others, and figuring out what to do with it. It would be good to start talking about a portal: good to have one place to remember, and be able to access all relevant documentation for there. Like on a Product Analytics Wikitech page..