It strikes me that dgraph is great at dealing with varied and inconsistent data and a lot of the queries you talk about seem perfectly doable. Sadly, if you want to search by hour rather than date there appears to be no built-in way to do that, as I found out when I asked a question specifically about this:
I now just have two datetime triples on my nodes: one for the date and one for the time. If you find a more elegant solution please let me know!