Yup, chapter 57 is probably not canon. That person above probably is misremembering stuff [She/He is human and thus flawed] and think Evie and Elsa did it in chapter 97 and forgot to read chapter 98 where Evie and Elsa talk about their feelings and why Evie is not ready to take the so-called 'next step' yet lol...Evie is totally fine with kissing, touching and hugging...Just the so-called 'last step' becuz in her explanation (Read ch.98) lol...*Shakes hand angry shouting at Evie's so-called morals*
Also from my point of view...Evie only call/mock/tease Elsa's body to try to get back at her teasing...Yeah probably not the smoothest or best comeback to teasing to Elsa's teasing but eh no human is perfect and people make mistakes that be a bit hurtful sometimes (Evie was flustered and embarrassed but then got over it probably to get back at Elsa). Not meant to be intentional hurtful or mean and Elsa obviously got over it soon after a few hours when Evie 'kind of' apologize. It kind of a dominance psychological thing that happen in some people relationship (Friends or lover- minor roast comment or fake insults, jokes).
Now for who to take the single position...Obviously Elsa is the best choice like Evie said, very talented once in a century existence in magic. The only issue and problem is if Elsa try over push and overexerted herself which is not a problem considering high MP/Mana...But it can happen if using ton and tons of MP (10-15+ people worth).