1. Who is Aibo?

2. He is a robot dog.
3. It is a robot dog.

4. What is Aibo?
5. He is a robot dog.
6. It is a robot dog.

(Are the questions and answers all correct? If the robot has a female voice, can we say " She is a robot dog?")

The sentences are fine. You would use 'He' or 'She' if it's clear the dog is male or female, yes. You would use 'It' if the dog's gender is unknown.