Does Umbraco already has an API that I can consume - for example in Angular?

What I need is, I want to put some select drop down in my website, and when the user selects, I want to send it to Angular app, and then to process the user selection inside the Angular app (therefore I need somehow to communicate in Angular and API will be the easiest way)

How can I obtain it?

Is the API is just as simple as wordpress that I can consume with a simple get ?

Another question: is there a way to embed Angular app within Umbraco website that it's not iFrame ?

Right now what I plan to do is just to build the same page in Angular, and once the user redirect to the Angular page, he'll have the same look and feel, and then inside the Angular app he'll have the functionality, and at any time he can go back to the magazine by either return to home page or click one of the top nav links which will bring him back to the Umbraco website - does it make sense? Is there a better way to do it?

Thanks