I like the composition.
I would still go with Dusty Miller over China Root cause ultimately they do the same Skill damage but Dusty has Skill Act. which buffs your damage consistency of your whole team.

On the other hand China Root's Counter could be nice for inflicting damage on enemy phase with her Counter (I think that was your intention,right? )
(Keep in mind on harder maps China Root might not be able to fire of her counter that often before she dies)

Yeah they both work. It depends what your personal preference is.

Btw. You can't have three Rainbow Roses in one team.
The game doesn't allow that. You can only have the same girl in three different Squads.

@Shad
I will write a few suggestions soon