Creating a Web Application With an API Backend

I'm just about to dive into a project and just need a little bit of guidance. My plan is to have a Google backend that is served through Cloud Endpoints as an API to a React.js frontend.

I've worked with the Google infrastructure for years, so I have no problem on the backend - but on the frontend, I have some questions.

I've never really touched React so I'm wondering whether it would work well for my needs (my needs being, consuming JSON on the frontend and rendering the data asynchronously)? My other question is, how is it possible to maintain a login system with an API outside of Google's Oauth2 that is tied to Google accounts?

Thanks!