Samsung SGH-D807 / D806

I am 99.9% sure that the D807 will be our next phones. I've not had a bluetooth phone yet and I am currious about a few things. First of all, I will be getting a Parrot Hansfree car kit installed in my wife's car. If her setup isn't as easy as possible, she'll never use it. The car kit will turn on and start "looking" for her phone as soon as the car is started...but what about the phone? Can she just leave the blutooth turned on all the time or will that kill her battery way too fast? How fast? How many steps are there to turn that feature on and off in the phone? Can a button be programmed as a shortcut to turn BT on & off quickly? Thanks for any replies!