At the moment we are preparing Clay integration for you. Once done you'd find a guideline how to use it easily.
Here is a full API - https://api.getsales.io/. Shortly we would release a dedicate API page right to the product with the most popular end point and simplified documentation. If you need help with API now, pls share the screenshot of your API request and error details, so we can help.
Webhooks can be set up in the settings/ webhooks. You can apply CRM filters to reach maximum granularity. You can track webhooks history from a dedicated page.