1. http://www.creationkit.com/SendAnimationEvent_-_Debug -> it's rubbish, unless you plan to kill the NPC straight after using it on ... it -> It's in a section called debug for a reason. I've no idea what it might do to the PC if you use it on that
(are you planning this for the player, an NPC, or both?)
But if you plan on this being a realtime effect, I don't think you've got much other choice? (Disable Player Controls and wotnot first)
2. You would be better doing the animation as a scene ... Then you can use http://www.creationkit.com/Idle_Animations (if you are lucky and a suitable one is there to find)
The scene goes in a repeatable quest, with another parent quest ... that you use to switch it on and off (plenty of examples on here of how to do that).
OnEffectStart of your spell start the Quest ... Script: Disable Player Controls, force 3rd person cam, enable an idle marker at player's feet, start scene ... play animation ... stop quest -> then in your OnEventFinish revert to a more normal (standing) idle ... stop quest, return to 1st person, return control to player (with suitable shaders or wotnot to mask the transitions)
(a scene would also work if spell is for NPC only ... and be much easier

)