The majority of bar mitzvot (pl) are celebrated in synagogues.
Of course Jews can have parties! Even the most devout orthodox Jews celebrate holidays and special occasions with music and dancing like everyone else! example: Bar Mitzvahs
Absolutely! Bar Mitzvahs are FAMILY events.
No
Bar mitzvahs are held at synagogues.
The food has to be kosher.
Everywhere
Yes.
Yes. Non Jews, when they attend Jewish events such as bar mitzvahs, weddings and funerals routinely wear a kippah. It is considered polite. Synagogues usually have a box of kippot (the correct plural), and sometimes, particularly at bar mitzvahs and weddings, guests are welcome to keep the kippot.
Jews celebrate a bar mitzvah when a boy turns 13 and becomes a official adult man/member of the community.
A 13 year old Jewish boy reads from the Torah and is considered a man. A seder (dinner) is afterward.
Yes people still held bar mitzvahs in the ghetto but they were very small and secretive so they wouldn't get caught.
They're celebrated with parties after the ceremony.