Generally we're able to apply hotfixes to certain IP ranges to override the standard ASN/ISP classification. When this is not possible we'll return 'block' = 2. Please read the API documentation for further information.
The API platform is hosted on two different locations in parallel. If the primary one fails DNS-based failover kicks in. Downtime should not exceed 5 minutes. Make sure your app doesn't crash if the API goes down.
You may want to check our API documentation website, where you can find some code examples.
Bitcoin Faucet owners can check this discussion.
Yes, but due to data saturation we don't recommend caching for more than 24 hours. Critical applications should cache for a maximum duration of 1 hour.