Auto Tranny Question

[MadOnion]

I finnally bought a mustang!
1989 GT Convertible, Auto, 80k, very clean engine. Lets just say I'm going to be very happy when I get all the paper work done.

Question is, when in town should I have it in Drive w/out the circle around it (second Drive down) Then on the highway put it in the uppermost drive?
I was told that Overdrive kicks in on the uppermost Drive.

The third drive down is low gears....
Is there any advantage to putting it in Low gears from a dead stop, then shift into the second drive when the rpms go up?
(If I wanted better times)

Thanks for the help!
If you want any details about the car, ask.... The car amazing!