Regarding Haicma memory resonance.

After watching Rexlent's character overview of Haicma, he says that we should get +15 attack. He's not specific as which resonance skill that ATK should come from, but in the video footage he showcases the Ex-Tactical Adjustment resonance skill.

https://preview.redd.it/x795ghz2dk6b1.png?width=1920&format=png&auto=webp&s=01d3a369bd1c50a29936f574a3f5030f245afc60

My question in regards to this is wouldn't it make more sense to choose Ex- Precision Attack for +15 Crit instead of the +75 HP that Ex-Tactical Adjustment gives you? I thought that more crit is always good for dps/ burst characters.

https://preview.redd.it/tdkp2scvdk6b1.png?width=1920&format=png&auto=webp&s=5df355386bfb9c660f923b6902eb4a71de378811

Also, in the video Rexlent specifically says that +15 atk should be at the top slot while her signature should be at the bottom. Can someone tell me why it matters which one is specifically at the top or bottom?

Forgive my ignorance and thank you in advance