Diaspora.
No. For most of the last 2,000 years, the Jews in Palestine were a repressed minority (or on occasion a repressed majority). Probably the most bloody period for Jews in Palestine was during the Crusades when Christian leaders slaughtered numerous Jews, especially in Jerusalem. However, Jews suffered other calamities in Palestine, such as the destruction of both Great Temples and the exile of significant portions of the Jewish population.
Because Palestine keeps attacking the Jews.
The Babylonians drove the Jews into their first exile. The Romans were the ones who caused the second and current exile period.
It depends on the exile in question. Most Jews that wanted to returned to Land of Israel after the exile in Babylonia on account of Cyrus the Great. Many Jews have returned to Israel in the last 150 years from the Roman Exiling of the Jews nearly 2000 years ago. However, not all Jews have returned home after exile in both cases.
Galut; exile; diaspora.
no
No. Jews had already been migrating to Israel/Palestine in substantial numbers since 1919.
There have always been Jews in Palestine. They were not the majority between the years 132 CE and 1949 CE.
The declaration gave the Jews of Palestine the hope that they might one-day have a country of their own.
Cyrus
no