Good luck with that first one. This isn't tech, this is every business since the beginning of business.
At least first class seems to skew toward the younger and hotter (but still competent). (Especially in Asian and Middle Eastern airlines where they haven't gone all PC yet.)
But mens' nature being what it is, we can expect that most (straight) men would rather have a flight attendant who's more
female / younger / attractive
and less
male / older / unattractive.