Installed the LEMP stack on a VPS running Ubuntu 16.4 & configured it to support Apache2 under reverse-proxy settings with .htaccess files on Port 8080. Would like to install Node.js server components to run on Port 8090. Is this possible? See this page for reference.
Yes, it is possible. You can install Node.js and set it to listen on port 8090 without a problem, as long as there is no other service listening on the same port.