You can turn off the various alerts via the navigation settings screen.
I agree the school zone warnings are a PITA, you'd think that any trainee computer programmer could have coded the system to have the school zone alerts only occur during various hours of the day and not on the weekends. Why should you be getting an alert at 11.00pm on a Saturday night.
Having the current speed zone being displayed would be extremely useful especially if it can be appear on the HUD display.