Wasn't it 2 keys per day or i am missing something?

About the popularity, from what i've read, more hearts mean the girls will follow the strategy you gave them more accuretly. But damn, i would hope a "shoot whatever you can hit more reliably" or "shoot lowest hp unit in range" would exist, because as of now, no matter what strategy pick, they still do pretty stupid movements that make S-ranking some maps a true hell unless you are way, way overleveled.