We can try :)
However the API is really designed for automation - I would find it very difficult to use ZAP as a manual security tool just using the API.
You could use the API to create a web based UI for ZAP that is more accessible.
We would like to do that but do not have enough volunteers to take it on.
Re proxying via ZAP, the main changes you need to make are to the app you want to proxy, e.g. your browser.
Browsers launched by ZAP are set up correectly, but I dont this we have API calls to launch browsers yet.
In order to see the requests proxied through ZAP use the "core" message views, e.g.