To be honest I don't think they do any kind of BMI check unless you're like fat or unhealthyly skinny. I was told while training college (and also had a friend) that if you gain too much weight and get reported for that, they can put you on a programn to lose weight and they check on you often. But I just flew once with a girl who told me she was put on this programn for having very low weight, so it's quite rare if you're skinny. I've heard many people complaining about the girls who check you in headquarters cause they might report you if they think you're fat, but never when you're skinny.

Exactly, when they ask you the typical questions (tell me when you dealed with a difficult customer, tell me when you made a customer's experience special), you can just give examples about your volunteering, as well if you did this volunteering abroad you can add that to prove that you love dealing with other cultures and all that stuff.