Hi! I am not sure of your role, but here are some general ideas.
Is there any way to edit items on my to-do list? You can edit items YOU add to the to-do list, but not items that are autogenerated from items generated by others, like the teacher of a course.
Can I remove items? You can remove items from the to-do list by clicking the x on the item. For Teachers, the item will return if there is another submission to an assignment.

Is there a way to add quizzes/etc directly to the to-do list? Add an item to your course calendar to add it to your to-do list.
Is there any plan to make a widget for the to-do list? I'm not sure about this one.
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