Want to use Reverse Proxy server for Nginx how can i?

I don’t want to use varnish cache, also apache as backend.

I need a reverse proxy for caching purpose to reduce backend process.

is FastCGI enough or extending FastCGI cache time and size works?

installing plugins like w3tc on all sites not suitable for me.

how can I use nginx as server & reverse proxy on the same machine?

is it possible?

also, I don’t have much idea about load balancers.

i know load balancers distribute load to another machine (is this machine are sperate servers)

is load balancing possible on the same stack?

I knew this points but confused

nginx already working as a reverse proxy to php-fpm-mysql.

full page caching with fast-cgi.