I simply rent a VPS, and I wish to install nginx like a server, however, the majority of the article on the web is use nginx like a reverse proxy, instead of like a server, what benefit with this particular configuration?

Can you really use 2 nginx (1 as reverse proxy another as server)?

another non-related this subject question, I am now using cpanel, how do i fully stop apache, since the httpd is definitely restart after sometimes, thanks.

What exactly are you going related to your Nginx? Should you simply want an internet server you are able to opt for only Nginx, that's fine.