She doesn't need any, her V1 buff will be deleted by a V5 QJ so it's usually better to keep her at V0.
A very needed upgrade as it will both boost her abitlity to keep dolls alive and boost their damage with burn boost and crit damage up.
It will also helps with her skill point income to use her ult more often. Once you get this, you can use her as the main healer for the fire team.