I have a /ping command add-on, that depending on what you give as arguments, you can either check your own ping, check another players ping, or admins can display a list of of everyone's ping to the server.
As for OP's suggestions, I don't believe there is a way for the server to get any of the required information from the client, so a server-side add-on wouldn't work.
As for a client-side add-on (if you can even get them to download it, you're better of just having them type 'metrics(fps);' in the console and tell them to look at a large group of bricks and see what their fps is) I'm not sure if there is a default way to get their video card information. As for an FPS estimate, they're a lot more to it than brick/light/poly count (the latter of which I'm not sure you can calculate)