Diablo – How does Bane of the Stricken work

I use Fists of Thunder for the gap closer and the 10% movespeed Passive as means to get more uptime for the Vortex - that gap closer and more mobility is the difference between the vortex falling off or not, a lot of the time.

Small chance, I guess, is because your base crit chance is low. I've noticed the skill stacking up on each crit I make - and using Crippling Wave as my 2nd autoattack, for example critting two enemies with a cleave will pump the aura to 3 instantly.

Continuous is based on your attack speed as is with many other "tick" based spells.

I also use the Dodge Mantra to not have to back out of a fight since you wan't to be there, letting the Vortex work it's magic for as long as you can. I also use Serenity (absorb all damage for 3 seconds) and Blinding Light as means to keep me out of harms way while steadily grinding down waves of foes with cleaving and the Vortex.

No, identical buffs/debuffs do not stack

Applying a buff or debuff that already exists simply refreshes the debuff already there

It should be noted that this is different for DoT debuffs. Per this post

The exception would be DOTS from multiple players. No player can reset/remove your DOT. Everyone has their own DOT counters, so you can apply the same DOT to one enemy as long as it is coming from two different sources.