ZSS Down Air question

[Chase Cooksey]

So I recently picked up ZSS and looked up some things for her.
I've noticed she has both a divekick and a hop on contact. I'm relatively sure the latter is her down air. So how does one go about doing the divekick?

 

[Axrz]

DownB + A or the Cstick

 

[Daftatt]

DownB + A or the Cstick

DRO DRO DRO DRO DROPPPIN KNOWLEDGE UP IN HERE

 

[0RLY]

The dive kick is down+b > A or c-stick.
Her dair is more of a stomp than a dive kick.
The footstool is down+b > B.