Are there nerves in human baby teeth?

Absolutely. And as a result baby teeth require the same exquisite care as permanent teeth. 1st dental check-up age 1 please.
Yes and more . There's arteries and veins too, and they have stem cells that fully matured adult teeth don't have. They can certainly hurt just like permanents, and is more delicate and fragile. They need expert care.
Yes. Important to maintain these teeth well so they do not decay. If decay is deep and involves the nerve, then often the teeth are extracted which can lead to problems with the development and eruption of their adult teeth.
Of course. They have canal that contains blood vessels and nerves.