Regarding the IF, the doll stays in inventory unless it's been changed unto a person. So heirs 4, 8, and 12 have to transform their dolls if they get the notification that it wants to come out and look around. However, with only 4 days as a toddler, that's less likely to happen.
Regarding career rewards, my understanding is that you could count the logic skill certificate only once, but that other heirs could max logic and sell the certificate.
Anyway, I'd say that Ambitions is necessary for this dynasty, especially if you have Seasons. I'm not sure a female heir can max a rabbit hole career before becoming an elder unless you have the workaholic trait.