she is a witch with some sort of weak aoe effect. Would show u some videos but can't find any english language of her. (also i'm a lazy bum). I guess u can use her as a witch , but it's easier to just field test her and see for yourself what's her attack pattern , and act on that. That's why i said to cc her fist instead of cloris. If u think she can[t fill a witch role well enough , then change places between the 2 , but i think mikoto should do pretty good as a witch.
Well it depends , since unless u have berna , cypria (u get her for free) is the best rogue in the game right now in terms of being a rogue. After AW , i'd argue for Ada since she becomes a beast , but shes an event unit which i guess u missed.
That being said , rogues are pretty situational so I at least don't use her a lot for combat.
That being said , cuterie increases the chance of female affection items drops if u take her on the team(u don't need to deploy or raise/cc her for her bonus) , and Betty gets a "gold get" passive per kill after Awakening , so she's usually used for gold income. Actually she's the unit i intend to awaken first in my team when we get to that. Awakening is literally another class evolution , that requires a crapload of resources and also needs to have your unit at max affection and max lvl (50cc60). Also awakening improves cuterie's passive as well , so keep that in mind.
In conclusion , to answer your question , i'd probably focus on Betty , since your main duelist won't be a rogue anyway (duh , u got clissa and olivie)