Got one in my Forza ad love it. It plugs into the diesel version of the OBD connector. My connector is round and under the dash next to the steering column. There is also another connector in the back next to the radiator. The amount and accuracy of the data depends on how many codes the engine computer supports. The older the engine, the fewer codes it supplies data for.
One down side is that it only supports 4 'guages' at a time. However, 2 units can be daisy-chained so you can read 8 'guages' if you wish.
Don't think you can attach it to any display device.
There are apps available for smart phones and tablets that do similar things. I have used one called Torque. Some use a OBD to bluetooth dongle for the connection. You can also lookup a product called Silverlight. A lot of folks like it.
Good Luck!