A few stellar swirl stat questions

Hey there!

New to Mizuki and I’ve been poking around the sub, but not sure entirely what is her bis artifact set? Is it the new one or is it 2pc2pc em? I also heard she needs crit, so am I doing a CD circlet or an em circlet?

I currently have nefer’s sig on Yae, so would it be better to keep it on her for a sandrone premium team, or better to give it to Mizuki? I have an R5 widsith to give to whoever isn’t using it.

Lastly, what stats should I be trying to aim for for her?

How much em? How much CR/CD?

Thank you so much!