Re: Leaving Key fob in vehicle
I would believe the Fob battery will not drain any faster left sitting in the GC, than if stored inside the house.
The Fob is "active" in that it is "constantly" tranmitting a signal, albeit not a very strong signal (the range is approximatly 3-5 feet in active/passive mode - ie when not pushing a button).
But the battery life in these new active/passive Fobs is less than old style Fobs that only transmit when you are pressing a button.
I still recommend changing the Fob batteries annually, and keeping a spare battery at home and another in the glovebox. You can purchase a 5-pack of CR2032 batteries for under $15. Pretty cheap maintenance and insurance.
And I agree that leaving the keys in your GC, even in your garage, is not a good idea. Just ask your insurance agent for the percentage of vehicles that are stolen, that have the keys in them. Many owners with garages leave the keys in the vehicle or hanging on a hook next to the door into the house, and many thieves are well aware of that...