Over reasonable distances and speeds, they hit at about the same time if dropped/fired horizontally from the same level since their downward acceleration is the same (even though the fired ball travels a much greater horizontal distance).
If you drop one cannon ball on the moon and fire the other cannon ball horizontally on the moon at very high speed, it will never hit the moon while the dropped one will.
Correct. And it might hit you in the back in head at some point... Unless it hits escape velocity.