Question about annoitment 'kills increase iron bear cooldown rate'

Hello Moze mains, I apologize for the basic question but I did not find the answer through our friendly neighbor search engine.
Can anyone explain how the annoitment ‘kills increase iron bear s cooldown rate by 30%’ works in details?
-Does it have a duration?
-Does each kill adds cool down rate?
-Does is stacks if it is both on weapon and shield?
-if it is on weapon does it count if you kill by others means like grenades?

Thanks a lot