Facebook Wi-Fi will not automatically display a splash page upon initial connection to your network. It will only load the splash page when a user attempts to access a website in a browser. All websites being accessed over HTTP (Port 80) will be redirected to the splash page.
Note: If a website or app utilizes HTTPS (Port 443) or any other ports/protocols aside from HTTP, it will bypass the splash page completely. Yahoo!, Google, and Gmail are examples of websites that send all traffic over HTTPS. This is by Facebook’s design and cannot be overridden.