The enzyme is found in bacterial plasma membrane, in thylakoid membrane (chloroplast ATP synthase) and in inner mitochondrial membrane. The main function of the enzyme is ATP production.
In this case, the terminal velocity increases to about 320 km/h (200 mph or 90 m/s), which is almost the terminal velocity of the peregrine falcon diving down on its prey.
1) Terminal velocity is never quite reached; a falling object will get closer and closer to terminal velocity. You can put some arbitrary limit, for which you can say that for all intents and purposes, terminal velocity has been reached, for example, 95%, or 99%, of terminal velocity.