I cannot even fathom reading without subvocalizing, though I suppose there are some very skilled people out there who can accomplish this. I do not hear the voices of any one else however, it is just my standard "thought voice."
Same. Inserting other voices sometimes happens, but only for deliberate effect in my own mind. Kind of like reading aloud with different voices and inflections would be. It is prompted by myself, not an involuntary thing.