How to use it, what it is in full detail is documented well and free. You sign up for the API key, not to view docs. i.e its not a sales funnel for people who arent interested

Also pretty sure you need to account for when you distribute the data, do you have the full rights to redistribute this data legally?

How do you prevent abuse and limit the call rate if you don't require an API key? Even with IP-based limits, I could programmatically pipe my calls through Tor.