Yes, radio button option can be none. For example, a multiple choice question that begins with no selection, or a group where "no selection" is also a valid selection.
Toggles haven't changed in like a year, I honestly don't remember what would be different. 3.0.8 is extremely out of date. I wish you had kept up with the updates a little more frequently. I do remember that the "startsChecked" is what the variable was before, and now it's "startsActive". Perhaps all you need to do is to ensure that all your toggles are using the updated field by checking and unchecking the state in inspector and re-saving the prefab.