I need to better understand the metrics that 3Scale collects and that we can see/analyze for individual users. All we can find so far on the site under STATS is "hits". What does a "hit" really mean?

The system can be configured to monitor any countable metric (hits, bandwidth, CPU time). "Hits" are meant to mean transactions on the API (any method), in the "API" > "Plans" section you can then define individual methods you want to track.

Tracking works by calling the 3scale API with single or batch traffic reports, these then get aggregated into the various boxes / time segments being tracked for your API.

If you’d like some help with setup, let us know at support@3scale.net and we’d be happy to help.