I use the due dates only as a day specific reminders. I have this tied to my calendar so they show in both Omnifocus and my calendar on that specific day. 90% of the time this does not require a time. Is there a way to turn off the due date time?
At what time would you expect an action without a due time to appear overdue? The answer to the question is usually what you should set your default due time to (and then let OmniFocus fill in that time automatically).
You can remove the notifications from any item individually via the inspector (see Mac screenshot below), or use OmniFocus Settings/Preferences to default them to off and then add custom notifications to the items you do want to be notified about.