O/D is 4th gear.
doesnt really come into factor of taking off.
-don't need it on for going up hill because you want to be in lower gear and good for MPG becuase at high speeds you want to be at low RPMs.
Unplug your battery for 5 min, restarting the computer, then drive the car like hell(like you want it to move) and the computer will learn the shift pattern. (a little trick I learned from KS