One way the Nazis determined if you were a Jew is if people had brown hair and brown eyes and where they lived. If they lived in a Jewish community then they where considered a Jew. Also, by their background like if they where born a Jew or had Jewish ancestors. If they converted to the Jewish religion they where taken to be a Jew.
No, because you can choose to be a Christian or not. It isn't something your born into like being a Jew or Catholic.
No he is not because the Torah says the only way the man can become Jewish is if he converts, he cannot marry a Jewish woman to become Jewish.
Some Holocaust survivors returned home and others did not. Some didn't even have a home to go to anymore. Many Jews went to "Displaced Persons Camps" which became their new home. Also, many Jews moved to Great Britain, France, Canada, and America to start a new beginning. The international community helped them by opening their borders and allowing them to move to their country. (http://night2007.wikispaces.com/Aftermath+of+the+Holocaust?f=print
By:E-Dizzle, Chop Suey, and Ray-D-Ation, Ashtard