Yes. He says so himself and follows the Jewish beliefs, he IS the line between Jewish and Christians
Of course Jesus was Jewish. Christianity was not established until after he was crucified.
Yes he was. Look it up. He couldn't have been the Messiah if he wasn't Jewish.
Yes, he was. At the beginning, there only was Judaism. Jews believe God is going to send us a Messiah: someone to save us. When Jesus was born, some of the Jews believed HE was the Messiah (Jesus also believed he was so, yes, he was Jewish). Those Jews who believed Jesus was the Messiah, were the ones who became Christians.
He also wasn't real but ok