The number listed after the localhost is the port number that the request is trying to connect to; port 8080 is the very common port for web traffic. Pretty much every computer should be able to use this port unless your network/computer has it blocked for some reason. If it is blocked then you would either need to unblock it or pick a different port to use on all computers.
The redirect URI can only be set to one thing per API Key. The only way to use different redirect URIs is to use multiple API Keys.