A live in nanny may be something for the ultra rich people, but I do not know anyone who actually has one. I also am middle class, so if it were a common thing, I would see it. You can create one and have them as part of your household. I often have multi-generational households where one set of grandparents help, which I find more realistic.
The more clothing and hair are achieved by owning more dlc, or if on computer, by cc. The lifespan are not long enough for me to care about more milestones. As for the needs, it is realistic to an actual infant, at least I believe it is since in reality I am a mother of 3 children.