So what do they do? Yes, that's right: they send the baby to a temple, one sufficiently far away from the family's manor. Lo and behold, the less-than-half-elf grew up decent (almost), strong and stubborn. (Blabla, Candy tired, must continue later...)
Note: Middy was originally a Faerūn-based character, but Candy has since decided to take her out of that context.
Yes, she inherited the luck.
Yes, she inherited the long lifespan... sorta.
Middy isn't immortal, like Sebbie, though still very long-lived. If she wasn't of Fochs blood, she would probably live up to 150 years, tops. As it now stands, her lifespan will likely be at least ten times that number. But she does age, albeit slowly - a few years for every century - and can, eventually, die of old age.