Amu Ult Bug

I'm pretty sure this was a one-time event however I turret dove and ulted on 2 enemy champs. It did go through (Team mates confirmed), we killed the enemy and I got away... my ult did not go on CD and I was able to use it again right away.

Second concern: The ult states that it prevents all attacks and movements. Does this include abilities (They do damage.. thus an attack)? I have ulted and still had players complete abilities that ended in my death. One that immediately comes to mind is a Lee Sin ult a fraction of a second AFTER my Amumu ult.

EDIT:

Third concern. His Q interaction with roots/snares https://youtu.be/UkvP6RMipVg

Skip to 3:20.