I'd be interested in replacing an in-house logs filtering/aggregation solution with Loki, but there's a lot that is not clear to me from the initial announcement & materials. Could you please help me understand what are the answers to the following questions?

- Can I use Loki without Prometheus? I'd like to feed raw logs to it, with custom-generated metadata. I don't want to have to use Prometheus, nor InfluxDB.

- Can I edit (modify) metadata for some old log line after it was already inserted? Specifically, I need to be able to rebuild metadata later, if I add some new "filters" to my logs (I want to be able to apply them retroactively).

- Can I run aggregate queries on the metadata (sum, avg, min/max)? If not, what can I do with the metadata? Can I graph the metadata on normal Grafana graphs?

- Is the text of the logs compressed? If yes, what compression algorithm is used? If not, why?

- Where can I find the API docs (or at least the API source code) for Loki?