For basic searching information, I found the Kibana Queries page, and the Lucene Syntax page are both quite useful.
As @magnusbaeck says, to do the clever aggregation, you'll have to query ES directly and handle the results.
For example, I use a POST request to the elasticsearch backend using something like curl or Postman. That way you can build all the filtering and aggregation in that you need. Admittedly, building the json for an aggregated search definition for ES can be a little daunting. I searched the internet for some tutorials, as the ES documentation is a little technical for my abilities.