Rakan/Xayah (W) Deadly Plumage interaction

Hello all,

I'm having trouble figuring out the Xayah/Rakan interaction with Xayah's (W) Deadly Plumage. I read the ability and even went to league of legends wiki to read up on it but nobody has been able to provide an explanation on the damage output.

ACTIVE: Xayah surrounds herself with a storm of feathers-blades for 4 seconds, granting her bonus attack speed. BONUS ATTACK SPEED: 30 / 35 / 40 / 45 / 50% Additionally, her basic attacks hurl lesser bolts from the storm, dealing 20% bonus physical damage to her target and granting 30% bonus movement speed for 1.5 seconds against champion. If Rakan Rakan is within 1000 units of Xayah, he will also gain Deadly Plumage, in turn causing each of their attacks to conjure a second lesser bolt from the other's storm and each will grant both of them bonus movement speed.

So when Xayah uses her Deadly Plumage does Rakan's bolts do damage base off of his AD or Xayah's?

Second questioon: Is there any interaction with Xayah's Deadly Plumage and

Thanks for feedback in advance