sayprimer.com actually can do this and deliver you CSV files for outbound. I just finished building the automated outbound process for MainStreet and it required no engineer and it will be automated. Happy to chat more about how I did this if you want.
I'm not entirely positive its what you would want but maybe take a look at Postman
not sure where you saw this, but usually they don't. worst case scenario is UAT.
I haven't actually tried that but you can build BDD style tests for APIs using Karate [1]. Your feature file could be technical, but you can wrap that in some accessible keywords for non-techies
[1] https://github.com/intuit/karate