Are you safe if let's say you go to pick up your kid from practice, and they take longer than expected so you park your vehicle and turn it off but not set foot out of said car?
Yes. You're OK in that circumstance.
But you can get a dui for having the keys in the ignition.
If you're worried about vicious dogs you should just carry a baseball bat or walking stick during the walk. Unless they are pit bulls (not that I have anything against pits, but they are strong dogs) you shouldn't have any problems.
Air horn. Dogs aren't scared of sticks, and fighting multiple dogs with a stick can easily be a losing game. Dogs ARE scared of ridiculously loud noises, and you can affect all dogs in the area at one time.
OP - My understanding of the law is you must be operating a vehicle. Picking up a child as a pedestrian would not qualify.
Whoa there, I would be careful on that one. The law specifically states that a person is only exempt while they are operating the vehicle. I wouldn't take the chance of shutting the engine off, even more so while pulling into a parking area, as you might no longer be considered to be operating the vehicle at that time. It may be splitting hairs, but that's precisely what prosecutors are good at. In the Newson case, while he actually exited the vehicle, he was specifically dinged because he was not actively operating the vehicle.
I imagine if you stay on the public sidewalk you'll be okay. Just don't step foot onto school property.