1. If you can't tell that a door is open either through it banging in the wind or the dome light being on, then the car is not the problem.
2. I taught my daughter to keep her seatbelt on, stay in her booster seat at all times, not to wind the window down (don't need the window lock out switch) and not to open her door while we're driving. It's not a police car, and she's not a prisoner. In the Subie and Mazda, we have "child lock out" switches, and we don't use them.
1998 C230 "Black Betty"