So just to be sure. 
( ive seen these questions be asked elsewhere and i feel like here also probably but no definitive answers yet)
1. what can u store? can u pocket a ballista shot?  
2. when u absorb it, does it retain the traits from the original user (ex: if a ranger tons of power& has the trait to slightly extend his range, is that also applied to the echoed projectile or is it based on ur traits/power? or if a champion mob who has a ridiculously powerful projectile attack, can that be stored and echoed?)