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.
It creeps up closer and closer, with the terminal velocity just being the limit. The time it takes to get very close to the terminal velocity VF is a few times VF/g, where g is the gravitational acceleration. Lee discusses that above. The actual form for the time-dependent velocity v(t) is v(t)+VF*tanh(gt/VF). See for more discussion.