How do you drive an automatic?

[MitchT]

Stupid question, I know. Obviously you put in in "D" and press the accelerator to go and the brake to stop.

However, I have never driven an auto and was wondering about a few of the more subtle elements...

1:
When you park a manual you can leave it in gear to provide more security than the handbrake alone provides. Does putting an auto in "P" effectively do the same thing? Does it lock the car "in gear" making it impossible to move because the engine is off?

2:
If you stop at traffic lights, etc., should you put an auto in "N"? I know with an automated manual with a paddle shift you're recommended to put it in neutral when you're stationary as the clutch will suffer excessive wear if it's in gear. I have no idea what an auto has that equates to a clutch, or if this can be worn excessively by leaving the car in "D" when stopped with the engine running.

3:
Why can't an auto be towed? I once had to be recovered and the breakdown guy on the phone asked if the car was a manual or an auto because autos can't be towed. Why? Surely an auto in "N" is the same as a manual in neutral.

[MitchT]

Thanks all, very helpful.

In terms of "not being able to remove the key if it's not in "P"... I guess that doesn't apply to a car with "keyless go".

[MitchT]

Interesting to know, particularly as it's the 4 Series that I'm interested in and the fact that most for sale seem to be autos has prompted my curiosity.