I would say that the main festival of the Jews is Shabbat as it is celebrated every week (yes just because it is followed every week does not make it any less ofa festival). It is the most important festival in family life and family is the center of Judaism. However Orthodox and Reform Judaism may have different thoughts on this.
There's no such holiday or concept in Judaism.
New year's is the main holiday in greece .
Yom Kippur
Kwanzaa is a Jewish holiday celebrated in december.
Reformed Judaism believes that the Bible is the main source for the rules of Judaism.
Israel.
Moses.
JUdaism
The Torah.
There is no such holiday called 'Haman'. Haman is a character in the story of Purim.
Judaism.See also:The origins of Purim
Abraham and Moses.