For the streaming part - there’s nothing in elastic for that. I’d suggest perhaps running an R instance that e.g., every second or few seconds, or more, queries your ES server, then proceed with data wrangling
Unfortunately, ES doesn’t have the concept of a changes feed like CouchDB has, but there is an open issue for it https://github.com/elastic/elasticsearch/issues/1242 and there is a apparently a plugin https://github.com/jurgc11/es-change-feed-plugin